- Ask a related questionWhat is a related question?A related question is a question created from another question. When the related question is created, it will be automatically linked to the original question.
Original question:
CCS/MSP-EXP430FR5994: UART echo back example return the character but with one second delay
Tool/software: Code Composer Studio
Hello,
In relation to the previous question here.
The attached program is based on the UART echo back example on pins P2.0, P2.1 from TIREX. (for the msp430fr5969, because currently there isn't one for the msp430fr5994 at TIREX).
That program is working well on the msp430fr5994 launchpad but not on my production board which currently doesn't have an external oscillator (actually it should have also external oscillator which identical to the one on the launchpad but for now we have some problem with that) so we just want to check the UART using the internal on-chip oscillator.
Is there an example of how to work with the UART but using the on-chip internal Oscillator?
Using driver lib.
Didn't find one on TIREX for the msp430fr5994, not for the MSP430fr5969.
Code:
/* --COPYRIGHT--,BSD
* Copyright (c) 2017, Texas Instruments Incorporated
* All rights reserved.
*
* 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.
* --/COPYRIGHT--*/
//******************************************************************************
//! EUSCI_A0 External Loopback test using EUSCI_A_UART_init API
//!
//! Description: This demo connects TX to RX of the MSP430 UART
//! The example code shows proper initialization of registers
//! and interrupts to receive and transmit data.
//!
//! ACLK = BRCLK = 32.768kHz, MCLK = SMCLK = DCO = ~1MHz
//!
//!
//! Tested on MSP430FR5969
//! -----------------
//! RST -| P2.0/UCA0TXD|----|
//! | | |
//! | | |
//! | P2.1/UCA0RXD|----|
//! | |
//!
//! This example uses the following peripherals and I/O signals. You must
//! review these and change as needed for your own board:
//! - UART peripheral
//! - GPIO Port peripheral (for UART pins)
//! - UCA0TXD
//! - UCA0RXD
//!
//! This example uses the following interrupt handlers. To use this example
//! in your own application you must add these interrupt handlers to your
//! vector table.
//! - USCI_A0_VECTOR.
//******************************************************************************
#include "driverlib.h"
uint16_t i;
uint8_t RXData = 0, TXData = 0;
uint8_t check = 0;
void main(void)
{
// stop watchdog
WDT_A_hold(WDT_A_BASE);
// LFXT Setup
//Set PJ.4 and PJ.5 as Primary Module Function Input.
/*
* Select Port J
* Set Pin 4, 5 to input Primary Module Function, LFXT.
*/
GPIO_setAsPeripheralModuleFunctionInputPin(
GPIO_PORT_PJ,
GPIO_PIN4 + GPIO_PIN5,
GPIO_PRIMARY_MODULE_FUNCTION
);
//Set DCO frequency to 1 MHz
CS_setDCOFreq(CS_DCORSEL_0,CS_DCOFSEL_0);
//Set external clock frequency to 32.768 KHz
CS_setExternalClockSource(32768,0);
//Set ACLK=LFXT
CS_initClockSignal(CS_ACLK,CS_LFXTCLK_SELECT,CS_CLOCK_DIVIDER_1);
//Set SMCLK = DCO with frequency divider of 1
CS_initClockSignal(CS_SMCLK,CS_DCOCLK_SELECT,CS_CLOCK_DIVIDER_1);
//Set MCLK = DCO with frequency divider of 1
CS_initClockSignal(CS_MCLK,CS_DCOCLK_SELECT,CS_CLOCK_DIVIDER_1);
//Start XT1 with no time out
CS_turnOnLFXT(CS_LFXT_DRIVE_0);
// Configure UART pins
//Set P2.0 and P2.1 as Secondary Module Function Input.
/*
* Select Port 2d
* Set Pin 0, 1 to input Secondary Module Function, (UCA0TXD/UCA0SIMO, UCA0RXD/UCA0SOMI).
*/
GPIO_setAsPeripheralModuleFunctionInputPin(
GPIO_PORT_P2,
GPIO_PIN0 + GPIO_PIN1,
GPIO_SECONDARY_MODULE_FUNCTION
);
/*
* Disable the GPIO power-on default high-impedance mode to activate
* previously configured port settings
*/
PMM_unlockLPM5();
// Configure UART
EUSCI_A_UART_initParam param = {0};
param.selectClockSource = EUSCI_A_UART_CLOCKSOURCE_ACLK;
param.clockPrescalar = 3;
param.firstModReg = 0;
param.secondModReg = 92;
param.parity = EUSCI_A_UART_NO_PARITY;
param.msborLsbFirst = EUSCI_A_UART_LSB_FIRST;
param.numberofStopBits = EUSCI_A_UART_ONE_STOP_BIT;
param.uartMode = EUSCI_A_UART_MODE;
param.overSampling = EUSCI_A_UART_LOW_FREQUENCY_BAUDRATE_GENERATION;
if (STATUS_FAIL == EUSCI_A_UART_init(EUSCI_A0_BASE, ¶m)) {
return;
}
EUSCI_A_UART_enable(EUSCI_A0_BASE);
EUSCI_A_UART_clearInterrupt(EUSCI_A0_BASE,
EUSCI_A_UART_RECEIVE_INTERRUPT);
// Enable USCI_A0 RX interrupt
EUSCI_A_UART_enableInterrupt(EUSCI_A0_BASE,
EUSCI_A_UART_RECEIVE_INTERRUPT); // Enable interrupt
__enable_interrupt();
while (1)
{
TXData = RXData; // Increment TX data
// Load data onto buffer
EUSCI_A_UART_transmitData(EUSCI_A0_BASE,
TXData);
while(check != 1);
check = 0;
}
}
//******************************************************************************
//
//This is the USCI_A0 interrupt vector service routine.
//
//******************************************************************************
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_A0_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_A0_VECTOR)))
#endif
void USCI_A0_ISR(void)
{
switch(__even_in_range(UCA0IV,USCI_UART_UCTXCPTIFG))
{
case USCI_NONE: break;
case USCI_UART_UCRXIFG:
RXData = EUSCI_A_UART_receiveData(EUSCI_A0_BASE);
check =1;
break;
case USCI_UART_UCTXIFG: break;
case USCI_UART_UCSTTIFG: break;
case USCI_UART_UCTXCPTIFG: break;
}
}Thanks.
Hi Ron,
I suspect what is happening is without the LFXT 32KHz crystal, the clock fault detection is switching to the LFMODCLK at powerup. The LFMODCLK is 1/128 of the MODOSC clock, which is centered around 4.8MHz and can vary quite a bit. Assuming it is 4.8MHz on your device the ACLK will be ~ 37.5Khz, not 32.768Khz..
Despite the clock frequency, you should be able to perform a loop-back test. Tie the TXD and RXD together and send some bytes out. You should receive the same without error since both transmit and receiving clocks are derived from the same ACLK source.
If you want to confirm communications with an external device, you will have to output the ACLK on on P2.0 and measure with an oscilloscope or logic probe to confirm the frequency. You can then adjust the baud rate parameters to generate your target baud rate and match the baud rate of the external device.
**Attention** This is a public forum
