TMS320F28388D: Difference in GPIO pin read delays observed for 'Boot from RAM' and 'Boot from Flash mode'

Aditya Padmanabha

Part Number: TMS320F28388D

Hi,

I am trying out a simple workflow for F2838x ControlCard checking the GPIO pins. In this case I have used external jumper and shorted GPIO10 and GPIO12. In the code I am configuring GPIO10 as input and GPIO 12 as output. I will set the value of GPIO12 and read the data from GPIO10 immediately to a variable. Here is the code I am using.

5415.gpio_ex1_setup.c

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//###########################################################################
//
// FILE:    gpio_ex1_setup.c
//
// TITLE:   Device GPIO Setup
//! <h1> Device GPIO Setup </h1>
//! \addtogroup bitfield_example_list
//!
//! Configures the F2838X GPIO into two different configurations
//! This code is verbose to illustrate how the GPIO could be setup.
//! In a real application, lines of code can be combined for improved
//! code size and efficiency.
//! This example only sets-up the GPIO.
//! Nothing is actually done with the pins after setup.
//
//#############################################################################
// $TI Release: F2838x Support Library v2.00.00.03 $
// $Release Date: Sun Sep 29 07:45:41 CDT 2019 $
// $Copyright:
// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
//
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions 
// are met:
// 
//   Redistributions of source code must retain the above copyright 
//   notice, this list of conditions and the following disclaimer.
// 
//   Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the 
//   documentation and/or other materials provided with the   
//   distribution.
// 
//   Neither the name of Texas Instruments Incorporated nor the names of
//   its contributors may be used to endorse or promote products derived
//   from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// $
//#############################################################################
//
// Included Files
//
#include "f28x_project.h"
//
// Defines
// Select the example to compile in.  Only one example should be set as 1
// the rest should be set as 0.
//
#define EXAMPLE1 0  // Basic pinout configuration example
#define EXAMPLE2 0  // Communication pinout example
//
// Function Prototypes
//
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

//###########################################################################
//
// FILE:    gpio_ex1_setup.c
//
// TITLE:   Device GPIO Setup
//! <h1> Device GPIO Setup </h1>
//! \addtogroup bitfield_example_list
//!
//! Configures the F2838X GPIO into two different configurations
//! This code is verbose to illustrate how the GPIO could be setup.
//! In a real application, lines of code can be combined for improved
//! code size and efficiency.
//! This example only sets-up the GPIO.
//! Nothing is actually done with the pins after setup.
//
//#############################################################################
// $TI Release: F2838x Support Library v2.00.00.03 $
// $Release Date: Sun Sep 29 07:45:41 CDT 2019 $
// $Copyright:
// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
//
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions 
// are met:
// 
//   Redistributions of source code must retain the above copyright 
//   notice, this list of conditions and the following disclaimer.
// 
//   Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the 
//   documentation and/or other materials provided with the   
//   distribution.
// 
//   Neither the name of Texas Instruments Incorporated nor the names of
//   its contributors may be used to endorse or promote products derived
//   from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// $
//#############################################################################

//
// Included Files
//
#include "f28x_project.h"

//
// Defines
// Select the example to compile in.  Only one example should be set as 1
// the rest should be set as 0.
//
#define EXAMPLE1 0  // Basic pinout configuration example
#define EXAMPLE2 0  // Communication pinout example

//
// Function Prototypes
//
void setupGPIOLoopBack(void);
void setup1GPIO(void);
void setup2GPIO(void);

Uint16 InputValue = 0;
Uint16 OutputValue = 0;

//
// Main
//

void main(void)
{
    //
    //Step 1. Initialize System Control:
    //PLL, WatchDog,enabe Peripheral Clocks
    //This example function is found in the f2838x_sysctrl.c file.
    //
    InitSysCtrl();

    //
    //Step 2. Initialize GPIO
    //
    InitGpio();

    //
    //Step 3. Clear all __interrupts and initialize PIE vector table:
    //Disable CPU __interrupts
    //
    DINT;

    //
    //Initialize the PIE control registers to their default state.
    //The default state is all PIE interrupts disabled and flags
    //are cleared.
    //
    InitPieCtrl();

    //
    //Disable CPU interrupts and clear all CPU interrupt flags:
    //
    IER = 0x0000;
    IFR = 0x0000;

    //
    //Initialize the PIE vector table with pointers to the shell Interrupt
    //Service Routines (ISR).
    //
    InitPieVectTable();

    //
    //Step 4. User specific code:
    //

    setupGPIOLoopBack();

#if EXAMPLE1

    //
    //This example is a basic pinout
    //
    setup1GPIO();

#endif

#if EXAMPLE2

    //
    // This example is a communications pinout
    //
    //setup2GPIO();

#endif

    while(1)
    {
        //ESTOP0;
        InputValue = 1;
        if (InputValue == 1)
          GpioDataRegs.GPASET.bit.GPIO12 = 1;
        else
          GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

        OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;

        DELAY_US(500000);

        InputValue = 1;
        if (InputValue == 1)
          GpioDataRegs.GPASET.bit.GPIO12 = 1;
        else
          GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

        OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;

        DELAY_US(500000);

        InputValue = 0;
        if (InputValue == 1)
          GpioDataRegs.GPASET.bit.GPIO12 = 1;
        else
          GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

        OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;

        DELAY_US(500000);

        InputValue = 0;
        if (InputValue == 1)
          GpioDataRegs.GPASET.bit.GPIO12 = 1;
        else
          GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

        OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;
    }
}

void setupGPIOLoopBack(void)
{


    //
    // Set GPIO10 as input and GPIO12 as output
    //
    EALLOW;

    GpioCtrlRegs.GPAPUD.bit.GPIO10 = 1;   // Disable pullup on GPIO10
    GpioCtrlRegs.GPAPUD.bit.GPIO12 = 1;   // Enable pullup on GPIO12
    GpioCtrlRegs.GPAMUX1.bit.GPIO10 = 0;  // GPIO10 = Input
    GpioCtrlRegs.GPAMUX1.bit.GPIO12 = 0;  // GPIO12 = Output

    //
    // Enable an GPIO output on GPIO12
    //
    //GpioDataRegs.GPASET.bit.GPIO12 = 1;   // Load output latch
    GpioCtrlRegs.GPADIR.bit.GPIO12 = 1;   // GPIO6 = output


    GpioCtrlRegs.GPAQSEL1.bit.GPIO10 = 0; // asynch input
    GpioCtrlRegs.GPAQSEL1.bit.GPIO12 = 0; // asynch input

    EDIS;
}

//
// setup1GPIO - Is an example that demonstrates the basic pinout
//
void setup1GPIO(void)
{
    //
    // Example 1: Basic Pinout.
    // This basic pinout includes:
    // PWM1-3, ECAP1, ECAP2, TZ1-TZ4, SPI-A, EQEP1, SCI-A, CAN-A, I2C
    // and a number of I/O pins
    // These can be combined into single statements for improved
    // code efficiency.
    //

    //
    // Enable PWM1-3 on GPIO0-GPIO5
    //
    EALLOW;
    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 0;   // Enable pullup on GPIO0
    GpioCtrlRegs.GPAPUD.bit.GPIO1 = 0;   // Enable pullup on GPIO1
    GpioCtrlRegs.GPAPUD.bit.GPIO2 = 0;   // Enable pullup on GPIO2
    GpioCtrlRegs.GPAPUD.bit.GPIO3 = 0;   // Enable pullup on GPIO3
    GpioCtrlRegs.GPAPUD.bit.GPIO4 = 0;   // Enable pullup on GPIO4
    GpioCtrlRegs.GPAPUD.bit.GPIO5 = 0;   // Enable pullup on GPIO5
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;  // GPIO0 = PWM1A
    GpioCtrlRegs.GPAMUX1.bit.GPIO1 = 1;  // GPIO1 = PWM1B
    GpioCtrlRegs.GPAMUX1.bit.GPIO2 = 1;  // GPIO2 = PWM2A
    GpioCtrlRegs.GPAMUX1.bit.GPIO3 = 1;  // GPIO3 = PWM2B
    GpioCtrlRegs.GPAMUX1.bit.GPIO4 = 1;  // GPIO4 = PWM3A
    GpioCtrlRegs.GPAMUX1.bit.GPIO5 = 1;  // GPIO5 = PWM3B

    //
    // Enable an GPIO output on GPIO6, set it high
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO6 = 0;   // Enable pullup on GPIO6
    GpioDataRegs.GPASET.bit.GPIO6 = 1;   // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO6 = 0;  // GPIO6 = GPIO6
    GpioCtrlRegs.GPADIR.bit.GPIO6 = 1;   // GPIO6 = output

    //
    // Enable eCAP1 on GPIO7
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO7 = 0;    // Enable pullup on GPIO7
    GpioCtrlRegs.GPAQSEL1.bit.GPIO7 = 0;  // Synch to SYSCLKOUT
    InputXbarRegs.INPUT7SELECT = 7;       // INPUT7 = GPIO7
    ECap1Regs.ECCTL0.bit.INPUTSEL = 7;    // Select eCAP1 TO INPUT7

    //
    // Enable GPIO outputs on GPIO8 - GPIO11, set it high
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO8 = 0;   // Enable pullup on GPIO8
    GpioDataRegs.GPASET.bit.GPIO8 = 1;   // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO8 = 0;  // GPIO8 = GPIO8
    GpioCtrlRegs.GPADIR.bit.GPIO8 = 1;   // GPIO8 = output

    GpioCtrlRegs.GPAPUD.bit.GPIO9 = 0;   // Enable pullup on GPIO9
    GpioDataRegs.GPASET.bit.GPIO9 = 1;   // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO9 = 0;  // GPIO9 = GPIO9
    GpioCtrlRegs.GPADIR.bit.GPIO9 = 1;   // GPIO9 = output

    GpioCtrlRegs.GPAPUD.bit.GPIO10 = 0;  // Enable pullup on GPIO10
    GpioDataRegs.GPASET.bit.GPIO10 = 1;  // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO10 = 0; // GPIO10 = GPIO10
    GpioCtrlRegs.GPADIR.bit.GPIO10 = 1;   // GPIO10 = output

    GpioCtrlRegs.GPAPUD.bit.GPIO11 = 0;  // Enable pullup on GPIO11
    GpioDataRegs.GPASET.bit.GPIO11 = 1;  // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO11 = 0; // GPIO11 = GPIO11
    GpioCtrlRegs.GPADIR.bit.GPIO11 = 1;  // GPIO11 = output

    //
    // Enable Trip Zone inputs on GPIO12 - GPIO14
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO12 = 0;   // Enable pullup on GPIO12
    GpioCtrlRegs.GPAPUD.bit.GPIO13 = 0;   // Enable pullup on GPIO13
    GpioCtrlRegs.GPAPUD.bit.GPIO14 = 0;   // Enable pullup on GPIO14
    GpioCtrlRegs.GPAQSEL1.bit.GPIO12 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL1.bit.GPIO13 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL1.bit.GPIO14 = 3; // asynch input
    InputXbarRegs.INPUT1SELECT = 12;      // GPIO12 = TZ1
    InputXbarRegs.INPUT2SELECT = 13;      // GPIO13 = TZ2
    InputXbarRegs.INPUT3SELECT = 14;      // GPIO14 = TZ3

    //
    // Enable SPI-A on GPIO16 - GPIO19
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO16 = 0;   // Enable pullup on GPIO16
    GpioCtrlRegs.GPAPUD.bit.GPIO17 = 0;   // Enable pullup on GPIO17
    GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0;   // Enable pullup on GPIO18
    GpioCtrlRegs.GPAPUD.bit.GPIO19 = 0;   // Enable pullup on GPIO19
    GpioCtrlRegs.GPAQSEL2.bit.GPIO16 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO17 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO18 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO19 = 3; // asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO16 = 1;  // GPIO16 = SPISIMOA
    GpioCtrlRegs.GPAMUX2.bit.GPIO17 = 1;  // GPIO17 = SPIS0MIA
    GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 1;  // GPIO18 = SPICLKA
    GpioCtrlRegs.GPAMUX2.bit.GPIO19 = 1;  // GPIO19 = SPISTEA

    //
    // Enable EQEP1 on GPIO's 20,21,22,23
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO20 = 0;   // Enable pullup on GPIO20
    GpioCtrlRegs.GPAPUD.bit.GPIO21 = 0;   // Enable pullup on GPIO21
    GpioCtrlRegs.GPAPUD.bit.GPIO22 = 0;   // Enable pullup on GPIO22
    GpioCtrlRegs.GPAPUD.bit.GPIO23 = 0;   // Enable pullup on GPIO23
    GpioCtrlRegs.GPAQSEL2.bit.GPIO20 = 0; // Synch to SYSCLKOUT
    GpioCtrlRegs.GPAQSEL2.bit.GPIO21 = 0; // Synch to SYSCLKOUT
    GpioCtrlRegs.GPAQSEL2.bit.GPIO22 = 0; // Synch to SYSCLKOUT
    GpioCtrlRegs.GPAQSEL2.bit.GPIO23 = 0; // Synch to SYSCLKOUT
    GpioCtrlRegs.GPAMUX2.bit.GPIO20 = 1;  // GPIO20 = EQEP1A
    GpioCtrlRegs.GPAMUX2.bit.GPIO21 = 1;  // GPIO21 = EQEP1B
    GpioCtrlRegs.GPAMUX2.bit.GPIO22 = 1;  // GPIO22 = EQEP1S
    GpioCtrlRegs.GPAMUX2.bit.GPIO23 = 2;  // GPIO23 = EQEP1I

    //
    // Enable eCAP1 on GPIO24
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO24 = 0;   // Enable pullup on GPIO24
    GpioCtrlRegs.GPAQSEL2.bit.GPIO24 = 0; // Synch to SYSCLKOUT
    InputXbarRegs.INPUT8SELECT = 24;      // INPUT8 = GPIO24
    ECap1Regs.ECCTL0.bit.INPUTSEL=8;      // Select eCAP1 TO INPUT8

    //
    // Set input qualification period for GPIO25 & GPIO26
    //
    GpioCtrlRegs.GPACTRL.bit.QUALPRD3=1;  // Qual period = SYSCLKOUT/2
    GpioCtrlRegs.GPAQSEL2.bit.GPIO25=2;   // 6 samples
    GpioCtrlRegs.GPAQSEL2.bit.GPIO26=2;   // 6 samples

    //
    // Make GPIO25 the input source for XINT1
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO25 = 0;  // GPIO25 = GPIO25
    GpioCtrlRegs.GPADIR.bit.GPIO25 = 0;   // GPIO25 = input
    GPIO_SetupXINT1Gpio(25);              // XINT1 connected to GPIO25

    //
    // Make GPIO26 the input source for XINT2
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO26 = 0;  // GPIO26 = GPIO26
    GpioCtrlRegs.GPADIR.bit.GPIO26 = 0;   // GPIO26 = input
    GPIO_SetupXINT2Gpio(26);              // XINT2 connected to GPIO26

    //
    // Make GPIO27 wakeup from STANDBY Low Power Modes
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO27 = 0; // GPIO27 = GPIO27
    GpioCtrlRegs.GPADIR.bit.GPIO27 = 0;  // GPIO27 = input
    CpuSysRegs.GPIOLPMSEL0.bit.GPIO27=1; // GPIO27 will wake the device
    CpuSysRegs.LPMCR.bit.QUALSTDBY = 2;  // Qualify GPIO27 by 2 OSCCLK
                                         // cycles before waking the device
                                         // from STANDBY

    //
    // Enable SCI-A on GPIO28 - GPIO29
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO28 = 0;   // Enable pullup on GPIO28
    GpioCtrlRegs.GPAQSEL2.bit.GPIO28 = 3; // Asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO28 = 1;  // GPIO28 = SCIRXDA
    GpioCtrlRegs.GPAPUD.bit.GPIO29 = 0;   // Enable pullup on GPIO29
    GpioCtrlRegs.GPAMUX2.bit.GPIO29 = 1;  // GPIO29 = SCITXDA

    //
    // Enable CAN-A on GPIO30 - GPIO31
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO30 = 0;   // Enable pullup on GPIO30
    GpioCtrlRegs.GPAMUX2.bit.GPIO30 = 1;  // GPIO30 = CANRXA
    GpioCtrlRegs.GPAPUD.bit.GPIO31 = 0;   // Enable pullup on GPIO31
    GpioCtrlRegs.GPAQSEL2.bit.GPIO31 = 3; // Asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO31 = 1;  // GPIO31 = CANTXA

    //
    // Enable I2C-A on GPIO32 - GPIO33
    //
    GpioCtrlRegs.GPBPUD.bit.GPIO32 = 0;   // Enable pullup on GPIO32
    GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 1;  // GPIO32 = SDAA
    GpioCtrlRegs.GPBQSEL1.bit.GPIO32 = 3; // Asynch input
    GpioCtrlRegs.GPBPUD.bit.GPIO33 = 0;   // Enable pullup on GPIO33
    GpioCtrlRegs.GPBQSEL1.bit.GPIO33 = 3; // Asynch input
    GpioCtrlRegs.GPBMUX1.bit.GPIO33 = 1;  // GPIO33 = SCLA

    //
    // Make GPIO34 an input
    //
    GpioCtrlRegs.GPBPUD.bit.GPIO34 = 0;  // Enable pullup on GPIO34
    GpioCtrlRegs.GPBMUX1.bit.GPIO34 = 0; // GPIO34 = GPIO34
    GpioCtrlRegs.GPBDIR.bit.GPIO34 = 0;  // GPIO34 = input

    EDIS;
}

//
// setup2GPIO - Is an example that demonstrates the communications pinout
//
void setup2GPIO(void)
{
    //
    // Example 2:
    // Communications Pinout.
    // This basic communications pinout includes:
    // PWM1-3, CAP2, SPI-B, CAN-A, SCI-A and I2C
    // and a number of I/O pins
    //

    //
    // Enable PWM1-3 on GPIO0-GPIO5
    //
    EALLOW;
    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 0;   // Enable pullup on GPIO0
    GpioCtrlRegs.GPAPUD.bit.GPIO1 = 0;   // Enable pullup on GPIO1
    GpioCtrlRegs.GPAPUD.bit.GPIO2 = 0;   // Enable pullup on GPIO2
    GpioCtrlRegs.GPAPUD.bit.GPIO3 = 0;   // Enable pullup on GPIO3
    GpioCtrlRegs.GPAPUD.bit.GPIO4 = 0;   // Enable pullup on GPIO4
    GpioCtrlRegs.GPAPUD.bit.GPIO5 = 0;   // Enable pullup on GPIO5
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;  // GPIO0 = PWM1A
    GpioCtrlRegs.GPAMUX1.bit.GPIO1 = 1;  // GPIO1 = PWM1B
    GpioCtrlRegs.GPAMUX1.bit.GPIO2 = 1;  // GPIO2 = PWM2A
    GpioCtrlRegs.GPAMUX1.bit.GPIO3 = 1;  // GPIO3 = PWM2B
    GpioCtrlRegs.GPAMUX1.bit.GPIO4 = 1;  // GPIO4 = PWM3A
    GpioCtrlRegs.GPAMUX1.bit.GPIO5 = 1;  // GPIO5 = PWM3B

    //
    // Enable an GPIO output on GPIO6
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO6 = 0;   // Enable pullup on GPIO6
    GpioDataRegs.GPASET.bit.GPIO6 = 1;   // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO6 = 0;  // GPIO6 = GPIO6
    GpioCtrlRegs.GPADIR.bit.GPIO6 = 1;   // GPIO6 = output

    //
    // Enable eCAP1 on GPIO7
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO7 = 0;    // Enable pullup on GPIO7
    GpioCtrlRegs.GPAQSEL1.bit.GPIO7 = 0;  // Synch to SYSCLKOUT
    InputXbarRegs.INPUT7SELECT = 7;       // INPUT7 = GPIO7
    ECap1Regs.ECCTL0.bit.INPUTSEL=7;      // Select eCAP1 TO INPUT7

    //
    // Enable GPIO outputs on GPIO8 - GPIO11, set it high
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO8 = 0;   // Enable pullup on GPIO8
    GpioDataRegs.GPASET.bit.GPIO8 = 1;   // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO8 = 0;  // GPIO8 = GPIO8
    GpioCtrlRegs.GPADIR.bit.GPIO8 = 1;   // GPIO8 = output

    GpioCtrlRegs.GPAPUD.bit.GPIO9 = 0;   // Enable pullup on GPIO9
    GpioDataRegs.GPASET.bit.GPIO9 = 1;   // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO9 = 0;  // GPIO9 = GPIO9
    GpioCtrlRegs.GPADIR.bit.GPIO9 = 1;   // GPIO9 = output

    GpioCtrlRegs.GPAPUD.bit.GPIO10 = 0;  // Enable pullup on GPIO10
    GpioDataRegs.GPASET.bit.GPIO10 = 1;  // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO10 = 0; // GPIO10 = GPIO10
    GpioCtrlRegs.GPADIR.bit.GPIO10 = 1;   // GPIO10 = output

    GpioCtrlRegs.GPAPUD.bit.GPIO11 = 0;  // Enable pullup on GPIO11
    GpioDataRegs.GPASET.bit.GPIO11 = 1;  // Load output latch
    GpioCtrlRegs.GPAMUX1.bit.GPIO11 = 0; // GPIO11 = GPIO11
    GpioCtrlRegs.GPADIR.bit.GPIO11 = 1;  // GPIO11 = output

    //
    // Enable SPI-B on GPIO22 - GPIO25
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO22 = 0;  // Enable pull-up on GPIO22 (SPICLKB)
    GpioCtrlRegs.GPAPUD.bit.GPIO23 = 0;  // Enable pull-up on GPIO23 (SPISTEB)
    GpioCtrlRegs.GPAPUD.bit.GPIO24 = 0;  // Enable pull-up on GPIO24 (SPISIMOB)
    GpioCtrlRegs.GPAPUD.bit.GPIO25 = 0;  // Enable pull-up on GPIO25 (SPISOMIB)
    GpioCtrlRegs.GPAQSEL2.bit.GPIO22 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO23 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO24 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO25 = 3; // asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO22 = 1;  // GPIO22 = SPICLKB
    GpioCtrlRegs.GPAMUX2.bit.GPIO23 = 1;  // GPIO23 = SPISTEB
    GpioCtrlRegs.GPAMUX2.bit.GPIO24 = 1;  // GPIO24 = SPISIMOB
    GpioCtrlRegs.GPAMUX2.bit.GPIO25 = 1;  // GPIO25 = SPISOMIB

    //
    // Enable SPI-A on GPIO16 - GPIO19
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO16 = 0;  // Enable pull-up on GPIO16 (SPISIMOA)
    GpioCtrlRegs.GPAPUD.bit.GPIO17 = 0;  // Enable pull-up on GPIO17 (SPISOMIA)
    GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0;  // Enable pull-up on GPIO18 (SPICLKA)
    GpioCtrlRegs.GPAPUD.bit.GPIO19 = 0;  // Enable pull-up on GPIO19 (SPISTEA)
    GpioCtrlRegs.GPAQSEL2.bit.GPIO16 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO17 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO18 = 3; // asynch input
    GpioCtrlRegs.GPAQSEL2.bit.GPIO19 = 3; // asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO16 = 1;  // GPIO16 = SPISIMOA
    GpioCtrlRegs.GPAMUX2.bit.GPIO17 = 1;  // GPIO17 = SPISOMIA
    GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 1;  // GPIO18 = SPICLKA
    GpioCtrlRegs.GPAMUX2.bit.GPIO19 = 1;  // GPIO19 = SPISTEA

    //
    // Enable eCAP2 on GPIO24
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO24 = 0;   // Enable pullup on GPIO24
    GpioCtrlRegs.GPAQSEL2.bit.GPIO24 = 0; // Synch to SYSCLKOUT
    InputXbarRegs.INPUT8SELECT = 24;      // INPUT8 = GPIO24
    ECap2Regs.ECCTL0.bit.INPUTSEL=8;      // Select eCAP2 TO INPUT8

    //
    // Set input qualifcation period for GPIO25 & GPIO26
    //
    GpioCtrlRegs.GPACTRL.bit.QUALPRD3=1;  // Qual period = SYSCLKOUT/2
    GpioCtrlRegs.GPAQSEL2.bit.GPIO25=2;   // 6 samples
    GpioCtrlRegs.GPAQSEL2.bit.GPIO26=2;   // 6 samples

    //
    // Make GPIO25 the input source for XINT1
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO25 = 0;  // GPIO25 = GPIO25
    GpioCtrlRegs.GPADIR.bit.GPIO25 = 0;   // GPIO25 = input
    GPIO_SetupXINT1Gpio(25);              // XINT1 connected to GPIO25

    //
    // Make GPIO26 the input source for XINT2
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO26 = 0;  // GPIO26 = GPIO26
    GpioCtrlRegs.GPADIR.bit.GPIO26 = 0;   // GPIO26 = input
    GPIO_SetupXINT2Gpio(26);              // XINT2 connected to GPIO26

    //
    // Make GPIO27 wakeup from HALT/STANDBY Low Power Modes
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO27 = 0; // GPIO27 = GPIO27
    GpioCtrlRegs.GPADIR.bit.GPIO27 = 0;  // GPIO27 = input
    CpuSysRegs.GPIOLPMSEL0.bit.GPIO27=1; // GPIO27 will wake the device
    CpuSysRegs.LPMCR.bit.QUALSTDBY = 2;  // Qualify GPIO27 by 2 OSCCLK
                                         // cycles before waking the device
                                         // from STANDBY

    //
    // Enable SCI-A on GPIO28 - GPIO29
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO28 = 0;   // Enable pullup on GPIO28
    GpioCtrlRegs.GPAQSEL2.bit.GPIO28 = 3; // Asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO28 = 1;  // GPIO28 = SCIRXDA
    GpioCtrlRegs.GPAPUD.bit.GPIO29 = 0;   // Enable pullup on GPIO29
    GpioCtrlRegs.GPAMUX2.bit.GPIO29 = 1;  // GPIO29 = SCITXDA

    //
    // Enable CAN-A on GPIO30 - GPIO31
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO30 = 0;   // Enable pullup on GPIO30
    GpioCtrlRegs.GPAMUX2.bit.GPIO30 = 1;  // GPIO30 = CANTXA
    GpioCtrlRegs.GPAPUD.bit.GPIO31 = 0;   // Enable pullup on GPIO31
    GpioCtrlRegs.GPAQSEL2.bit.GPIO31 = 3; // Asynch input
    GpioCtrlRegs.GPAMUX2.bit.GPIO31 = 1;  // GPIO31 = CANRXA

    //
    // Enable I2C-A on GPIO32 - GPIO33
    //
    GpioCtrlRegs.GPBPUD.bit.GPIO32 = 0;   // Enable pullup on GPIO32
    GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 1;  // GPIO32 = SDAA
    GpioCtrlRegs.GPBQSEL1.bit.GPIO32 = 3; // Asynch input
    GpioCtrlRegs.GPBPUD.bit.GPIO33 = 0;   // Enable pullup on GPIO33
    GpioCtrlRegs.GPBQSEL1.bit.GPIO33 = 3; // Asynch input
    GpioCtrlRegs.GPBMUX1.bit.GPIO33 = 1;  // GPIO33 = SCLA

    //
    // Make GPIO34 an input
    //
    GpioCtrlRegs.GPBPUD.bit.GPIO34 = 0;  // Enable pullup on GPIO34
    GpioCtrlRegs.GPBMUX1.bit.GPIO34 = 0; // GPIO34 = GPIO34
    GpioCtrlRegs.GPBDIR.bit.GPIO34 = 0;  // GPIO34 = input

    EDIS;
}

//
// End of File
//

The input sequence for the variable InputValue (GPIO12) will be [1 1 0 0 ] but the output sequence I observe for Boot from RAM mode is OutputValue = [0 1 1 0] but the output sequence observed for Boot from Flash mode is OutputValue = [1 1 1 0].

Boot from RAM, here we are observing the delay in updating the change for 0 to 1 as well as 1 to 0. This looks like the GPIO data will be updated after the execution of the instruction OutputValue = GpioDataRegs.GPADAT.bit.GPIO10; Hence the delay is observed for both the transitions.
Boot from Flash, here we are observing the delay only in the transition from 1 to 0. The 0 to 1 transition looks proper and is immediately reflected. I am not sure what is the order of execution of statement OutputValue = GpioDataRegs.GPADAT.bit.GPIO10; before or after data is updated for GPIO10.

Is this expected behavior? What is the recommended workflow in these cases?

Thanks,

Aditya

over 5 years ago

0 Nima Eskandari over 5 years ago

TI__Guru 52020 points

Manoj Santha Mohan

Can you comment on this?

0 Nima Eskandari over 5 years ago in reply to Nima Eskandari

TI__Guru 52020 points

Have you configured your flash wait states?

0 Aditya Padmanabha over 5 years ago in reply to Nima Eskandari

Expert 1440 points

Hi Nima,

In the attached code, the InitSysCtrl function is called first which in turn should call the function InitFlash, if _FLASH is configured. This function I think will configure the required wait state as per the logic below.

//
// Set waitstates according to frequency
//
// *CAUTION*
// Minimum waitstates required for the flash operating at a given CPU rate
// must be characterized by TI. Refer to the datasheet for the latest
// information.
//
#if CPU_FRQ_200MHZ
Flash0CtrlRegs.FRDCNTL.bit.RWAIT = 0x3;
#endif

#if CPU_FRQ_150MHZ
Flash0CtrlRegs.FRDCNTL.bit.RWAIT = 0x2;
#endif

#if CPU_FRQ_120MHZ
Flash0CtrlRegs.FRDCNTL.bit.RWAIT = 0x2;
#endif

Thanks,

Aditya

0 Nima Eskandari over 5 years ago in reply to Aditya Padmanabha

TI__Guru 52020 points

Run through code, single stepping and make sure these lines get executed.

Nima

0 Aditya Padmanabha over 5 years ago in reply to Nima Eskandari

Expert 1440 points

Hi Nima,

Yes I have stepped through these lines of code. The flash wait states configuration are executed properly.

Thanks,

Aditya

0 Nima Eskandari over 5 years ago in reply to Aditya Padmanabha

TI__Guru 52020 points

Vivek Singh Do you know what is causing this?

0 Vivek Singh over 5 years ago in reply to Nima Eskandari

TI__Guru** 113745 points

Aditya,

You are executing this in while (1) loop. How are you observing the value for OutputValue at different time ? Can you have four different variables for each assignment so that it is more clear ?

Regards,

Vivek Singh

0 Aditya Padmanabha over 5 years ago in reply to Vivek Singh

Expert 1440 points

Hi Vivek,

This is the while loop we have in the code.

while(1)
{
InputValue = 1;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;

DELAY_US(500000);

InputValue = 1;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;

DELAY_US(500000);

InputValue = 0;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;

DELAY_US(500000);

InputValue = 0;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;
}

In order to observe the behavior I put break points at 4 places.

1) At the first line of code inside the loop - InputValue = 1;

2) 3) and 4) At the 3 delays I have in the loop - DELAY_US(500000);

Every time I observe OutputValue and compare with the input value we set. This value varies when I do boot from Flash or RAM.

Yes if you want to replicate, you can change the code and have four different values of OutputValue as shown below to observe the behavior more clearly.

Uint16 OutputArray[4] = { 0, 0, 0, 0 };

while(1)
{
InputValue = 1;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;
OutputArray[0] = OutputValue;

DELAY_US(500000);

InputValue = 1;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;
OutputArray[1] = OutputValue;

DELAY_US(500000);

InputValue = 0;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;
OutputArray[2] = OutputValue;

DELAY_US(500000);

InputValue = 0;
if (InputValue == 1)
GpioDataRegs.GPASET.bit.GPIO12 = 1;
else
GpioDataRegs.GPACLEAR.bit.GPIO12 = 1;

OutputValue = GpioDataRegs.GPADAT.bit.GPIO10;
OutputArray[3] = OutputValue;
}

Thanks,

Aditya

0 Nima Eskandari over 5 years ago in reply to Aditya Padmanabha

TI__Guru 52020 points

Have you been able to resolve this?

0 Aditya Padmanabha over 5 years ago in reply to Nima Eskandari

Expert 1440 points

Hi Nima,

The issue is still present.

Thanks,

Aditya

0 Vivek Singh over 5 years ago in reply to Aditya Padmanabha

TI__Guru** 113745 points

Hi Aditya,

Please confirm that GPIO12 is correctly configured as output by looking at DIR register value in CCS register view after configuration is done.

There is always some delay between output to input captured and it can take few cycles to update the value in input register after output value is set. To confirm this, can you insert some delay before reading the value (you can use DEALY function) and see if that helps in getting consistent value.

Regards,

Vivek Singh

0 Aditya Padmanabha over 5 years ago in reply to Vivek Singh

Expert 1440 points

Hi Vivek,

Yes all the pin are configured correctly. I have confirmed that in CCS.

Yes I do understand that there will be a delay of few cycles to update the value in input register after the output I set. And I have confirmed the same in my initial post. My question was specifically to understand the difference in the data read between Boot from Flash and Boot from RAM when delay is not used.

Boot from RAM, here we are observing the delay in updating the change for 0 to 1 as well as 1 to 0. This looks like the GPIO data will be updated after the execution of the instruction OutputValue = GpioDataRegs.GPADAT.bit.GPIO10; Hence the delay is observed for both the transitions.
Boot from Flash, here we are observing the delay only in the transition from 1 to 0. The 0 to 1 transition looks proper and is immediately reflected. I am not sure what is the order of execution of statement OutputValue = GpioDataRegs.GPADAT.bit.GPIO10; before or after data is updated for GPIO10.

Thanks,

Aditya

0 Aditya Padmanabha over 5 years ago in reply to Aditya Padmanabha

Expert 1440 points

Hi Vivek,

If we observe the sequence as explained above the different delays observed for transition from 1 to 0 and 0 to 1. But in data sheet I see that rise time and fall time for GPIO Output pins are same. (Chapter 5.8.6.1 GPIO - Output Timing, Table 5-21. General-Purpose Output Switching Characteristic)

Thanks,

Aditya

0 Nima Eskandari over 5 years ago in reply to Aditya Padmanabha

TI__Guru 52020 points

Do you have any external connections on the GPIOs?

Nima

0 Aditya Padmanabha over 5 years ago in reply to Nima Eskandari

Expert 1440 points

Hi Nima,

Other than the jumper wires connecting GPIO10 and GPIO12 I don't have any thing else connected.

Thanks,

Aditya

0 Nima Eskandari over 5 years ago in reply to Aditya Padmanabha

TI__Guru 52020 points

Were you able to resolve this? I don't have any further recommendations.

Vivek Singh Jason Whiles anything from your side on this topic?

0 Aditya Padmanabha over 5 years ago in reply to Nima Eskandari

Expert 1440 points

Hi Nima,

I wanted to understand if this behavior is reproducible from TI side as well. If yes, is the behavior due to some software settings or hardware behavior?

If it is software then we can arrive at some solution or fix to solve the issue. (Looks like it is not as we verified different register combination in our discussions above.)

If it is hardware then at least this behavior can be documented for others.

I am ok to close this post. But it would be good to arrive at some conclusion for benefit of others in future.

Thanks,

Aditya

0 Jason Whiles over 5 years ago in reply to Aditya Padmanabha

TI__Expert 5240 points

Aditya,

As you noted there is some transport delay between setting the output and seeing the results back on an input. For predictable testing here you should add a DELAY_US() statement before the OutputValue = GpioDataRegs.GPADAT.bit.GPIO10 . If these are back to back without delay then there will be variable results that could be influenced by many things.

Best regards,

Jason

0 Frank Ankapong over 5 years ago in reply to Aditya Padmanabha

TI__Mastermind 28275 points

Hi Aditya,

Besides the delay required, when setting and clearing GPIOs, it's recommended to use GPxSET and GPxCLEAR instead of GPxDAT. The read-modify-write that is performed in bitfield operations can have unintended consequences when GPxDAT is used to set and clear GPIOs.

0 Aditya Padmanabha over 5 years ago in reply to Frank Ankapong

Expert 1440 points

Hi All,

Thanks for your suggestions on this issue. We can close this discussion.

Regards,

Aditya

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28388D: Difference in GPIO pin read delays observed for 'Boot from RAM' and 'Boot from Flash mode'