• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Subscribers 31 subscribers
  • Views 1227 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TIVA TM4C123H6P GPIO+DMA

Tankist
Expert 1690 points
Other Parts Discussed in Thread: TM4C1233H6PM

I want to use DMA for reading information from GPIO (for example, from GPIOD) pins. I tried to do that but I've got a fault: I always read 0 instead of the real state, but if I read it manually I get a good result.

Trigger for the DMA transaction is Timer 0 or manual trigger.

Is it generally possible?

  • 0
    TI__Guru**** 244400 points
    Hello Tankist,

    It is possible to have a trigger from one peripheral to read another peripheral. Have you enabled the clock to the GPIO. No code????

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Expert 1690 points

    There is the source code for the part of my application. The controller works on 80 MHz.

    Fullscreen text.txt Download 
    // DMA channel
#define DMA_CHANNEL		UDMA_CHANNEL_TMR0A
// buffer size
#define DMA_BUF_SIZE	100

// quantisation frequency
unsigned long ulFrequency = 8000;

// input buffer to store values from port D
uint16_t gpio_buf[DMA_BUF_SIZE];

// this is necessary
#pragma data_alignment=1024
unsigned char ucControlTable[1024];

// -------------------------- subroutines ----------------------------------

void timer_init()
{
	unsigned long ulPeriod;

    // switch TIMER clock on
	SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
	// full width timer
	TimerConfigure(TIMER0_BASE, TIMER_CFG_32_BIT_PER);
	// calculate the period
	ulPeriod = (80000000UL / ulFrequency);
	TimerLoadSet(TIMER0_BASE, TIMER_A, ulPeriod - 1);
}

void timer_enable()
{
	// enable my timer
	TimerEnable(TIMER0_BASE, TIMER_A);
}

void dma_init(void)
{
	// fill the buffer with a constant: I can watch transactions in the WatchWindow
	memset(gpio_buf, 0xFF, sizeof(gpio_buf));
	
	// enable of the monitoring port
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
    GPIOPinTypeGPIOInput(GPIO_PORTD_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);

    // switch DMA clock on
    SysCtlPeripheralEnable(SYSCTL_PERIPH_UDMA);
    uDMAEnable();
    uDMAControlBaseSet(ucControlTable);
	
    // fill attributes
    uDMAChannelAttributeDisable(DMA_CHANNEL,
    		UDMA_ATTR_ALTSELECT
    		| UDMA_ATTR_USEBURST
    		| UDMA_ATTR_REQMASK
    		| UDMA_ATTR_HIGH_PRIORITY);

    // primary transaction set
    uDMAChannelControlSet(DMA_CHANNEL | UDMA_PRI_SELECT,
    		UDMA_SIZE_16 |				// word size
    		UDMA_SRC_INC_NONE |			// from register (GPIO_PORTD_BASE + GPIO_O_DATA) so constant
    		UDMA_DST_INC_16 |			// destination in memory so increment
    		UDMA_ARB_1);				// one word per transaction
   	// primary transfer set
    uDMAChannelTransferSet(DMA_CHANNEL | UDMA_PRI_SELECT,
    		UDMA_MODE_BASIC,			// linear filling
            (void *)(GPIO_PORTD_BASE + GPIO_O_DATA),	// GPIOD data register
            gpio_buf,					// my buffer
            DMA_BUF_SIZE);				// buffer size
  
	// enable DMA - waiting for the trigger event
    uDMAChannelEnable(DMA_CHANNEL);
}

// ------------------------- main application function -----------------------------
void board_init()
{
	timer_init();	// setup a timer - it doesn't work now
	dma_init();		// setup DMA - it suspend for some events
	timer_enable();	// start my timer - since that all transactions happen

	IntMasterEnable();
}

  • 0 in reply to Tankist
    TI__Guru**** 244400 points

    Hello Tankist

    I ran the program with one change (I could not find where you got TIMER_CFG_32_BIT_PER  from)

    TimerConfigure(TIMER0_BASE, TIMER_CFG_32_BIT_PER);

    to

    TimerConfigure(TIMER0_BASE, TIMER_CFG_PERIODIC);

    And the DMA transfer completes without bus faults.

    Attached is a simplified code that I ran on my setup.

    Fullscreen ektm4c123_timer_uart.c Download 
    #include <stdbool.h>
#include <stdint.h>
#include "inc/hw_gpio.h"
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/timer.h"
#include "driverlib/udma.h"
#include "utils/uartstdio.h"

// DMA channel
#define DMA_CHANNEL		UDMA_CHANNEL_TMR0A
// buffer size
#define DMA_BUF_SIZE	100

// quantisation frequency
unsigned long ulFrequency = 8000;

// input buffer to store values from port D
uint16_t gpio_buf[DMA_BUF_SIZE];

// this is necessary
#pragma DATA_ALIGN(ucControlTable, 1024)
unsigned char ucControlTable[1024];

void timer_init()
{
	unsigned long ulPeriod;

    // switch TIMER clock on
	SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
	// full width timer
	TimerConfigure(TIMER0_BASE, TIMER_CFG_PERIODIC); //TIMER_CFG_32_BIT_PER
	// calculate the period
	ulPeriod = (80000000UL / ulFrequency);
	TimerLoadSet(TIMER0_BASE, TIMER_A, ulPeriod - 1);
}

void timer_enable()
{
	// enable my timer
	TimerEnable(TIMER0_BASE, TIMER_A);
}

void dma_init(void)
{
	// enable of the monitoring port
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
    GPIOPinTypeGPIOInput(GPIO_PORTD_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);

    // switch DMA clock on
    SysCtlPeripheralEnable(SYSCTL_PERIPH_UDMA);
    uDMAEnable();
    uDMAControlBaseSet(ucControlTable);

    // fill attributes
    uDMAChannelAttributeDisable(DMA_CHANNEL,
    		UDMA_ATTR_ALTSELECT
    		| UDMA_ATTR_USEBURST
    		| UDMA_ATTR_REQMASK
    		| UDMA_ATTR_HIGH_PRIORITY);

    // primary transaction set
    uDMAChannelControlSet(DMA_CHANNEL | UDMA_PRI_SELECT,
    		UDMA_SIZE_16 |				// word size
    		UDMA_SRC_INC_NONE |			// from register (GPIO_PORTD_BASE + GPIO_O_DATA) so constant
    		UDMA_DST_INC_16 |			// destination in memory so increment
    		UDMA_ARB_1);				// one word per transaction
   	// primary transfer set
    uDMAChannelTransferSet(DMA_CHANNEL | UDMA_PRI_SELECT,
    		UDMA_MODE_BASIC,			// linear filling
            (void *)(GPIO_PORTD_BASE + GPIO_O_DATA),	// GPIOD data register
            gpio_buf,					// my buffer
            DMA_BUF_SIZE);				// buffer size

	// enable DMA - waiting for the trigger event
    uDMAChannelEnable(DMA_CHANNEL);
}


int
main(void)
{
    //
    // Set the clocking to run directly from the external crystal/oscillator.
    // TODO: The SYSCTL_XTAL_ value must be changed to match the value of the
    // crystal on your board.
    //
    SysCtlClockSet(SYSCTL_SYSDIV_2_5 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
                   SYSCTL_XTAL_16MHZ);

	timer_init();	// setup a timer - it doesn't work now
	dma_init();		// setup DMA - it suspend for some events
	timer_enable();	// start my timer - since that all transactions happen

	IntMasterEnable();

	//
    // Loop forever while the PWM signals are generated.
    //
    while(1)
    {
    }
}

    Regards

    Amit

  • 0 in reply to Amit Ashara
    Expert 1690 points

    I'm sorry for the involuntary fraud, it was mistake in the name of the processor. My device's name is LX4F120H5QRF. It's old part so I meant TM4C1233H6PM as the analog, but I've done a mistake in the name. I use Stellaris Library for the chip supporting which may consist different definitions like TIMER_CFG_32_BIT_PER. This device is exactly Cortex-M4 processor so I put my question in this thread.

    Maybe I badly described my problem. As I see DMA works (values in gpio_buf change its state during working), but works incorrectly. The problem is values that DMA stores in gpio_buf doesn't match real signals on controller's pins. It seems like DMA reads from the wrong register. There are some screenshots from my IDE:

    1) State of gpio_buf before timer_enable();

    2) State of gpio_buf after timer_enable();

    As you can see it fills so I'm sure that DMA works.

    3) State of the GPIOD data register (source of DMA transactions):

    As you can see the one pin has the high level so it's impossible to get a value equal to 0 after the DMA transaction.

    I expect that I'll get a value 0x0004 in my buffer, but it isn't so. Amit, could you check does it work properly on your platform?

  • 0 in reply to Tankist
    TI__Guru**** 244400 points
    Hello Tankist,

    The GPIO module uses bit banded scheme to read pins (details in the data sheet). The define GPIO_O_DATA is 0x0 and this will cause it to read 0x0 always even though the GPIODDATA shows 0x4. Instead of using GPIO_O_DATA in the UDMA source buffer use the offset 0x3FC

    uDMAChannelTransferSet(DMA_CHANNEL | UDMA_PRI_SELECT,
    UDMA_MODE_BASIC, // linear filling
    (void *)(GPIO_PORTD_BASE + 0x3FC), // GPIOD data register
    gpio_buf, // my buffer
    DMA_BUF_SIZE); // buffer size

    I will file a bug for this correction of GPIO_O_DATA to be 0x3FC.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Expert 1690 points
    Amit, thank you very much! Now it works well.
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Hi Amit,

    (Another) great "get" - we missed this as well - thank you.

    (we note that our "fraud" was far from vouluntary...[cell door slams shut])

  • 0 in reply to cb1
    TI__Guru**** 244400 points
    Hello cb1, All

    There was a bit of complication in modifying the underlying API call for GPIOPinRead and GPIOPinWrite, but it seems that we can work it out by using a SUB instruction (when compiled and linked). However it would need to approved for fix.

    Regards
    Amit