topic Re: LPC1549: How to use the DMA with the ADC in LPC Microcontrollers

LPC1549: How to use the DMA with the ADC

jespermadsen — Tue, 19 Jan 2021 08:14:40 GMT

I found this example:

https://community.nxp.com/t5/LPC-Microcontrollers-Knowledge/DMA-Ping-Pong-application/ta-p/1120977

for the LPCXpressor54114 Board and changed it to match the LPC1549 LPCXpresso™ board.

There are some ADC results in the buffer. But there are zeros and not compleately processed data there too.

I'm using the SCT2_Out3 to ADC0_SEQA to DMA. I'm not sure if the ADC_SEQA is setup correctly.

What could be wrong?

The code is shown below:

//-------------------------------------------------------------

#if defined (__USE_LPCOPEN)
#if defined(NO_BOARD_LIB)
#include "chip.h"
#else
#include "board.h"
#endif
#endif

#include <cr_section_macros.h>

#define NUM_BUFFERS 4
#define DMA_TRANSFER_SIZE 8
#define ADC_INPUT_CHANNEL 0

#define SCT_PWM_RATE 10000 /* PWM frequency 10 KHz */
#define SCT_PWM_PIN_OUT 3 /* COUT3 Generate square wave */
#define SCT_PWM_OUT 3 /* Index of OUT PWM */

uint16_t adcOut;

DMA_CHDESC_T ADC_TransferDescriptors[NUM_BUFFERS] __attribute__ ((aligned(512)));

uint16_t CapturedData[32];

uint16_t DMA_Sum=0;

/**
*
* ADC IRQ not Used right now... Only for testing
*/
void ADC_SEQA_IRQHandler(void)
{
/* If SeqA flags is set i.e. data in global register is valid then read it */
Chip_ADC_ClearFlags(LPC_ADC0,0xFFFFFFFF);
}

void DMA_IRQHandler(void)
{
static uint16_t DMA_Sum=0;

DMA_Sum++;

if(DMA_Sum ==8)
{
DMA_Sum=4;
}

/* Rrror interrupt on channel 0? */
if ((Chip_DMA_GetIntStatus(LPC_DMA) & DMA_INTSTAT_ACTIVEERRINT) != 0)
{
/* This shouldn't happen for this simple DMA example, so set the LED
to indicate an error occurred. This is the correct method to clear
an abort. */
Chip_DMA_DisableChannel(LPC_DMA, DMA_CH0);
while ((Chip_DMA_GetBusyChannels(LPC_DMA) & (1 << DMA_CH0)) != 0) {}
Chip_DMA_AbortChannel(LPC_DMA, DMA_CH0);
Chip_DMA_ClearErrorIntChannel(LPC_DMA, DMA_CH0);
Chip_DMA_EnableChannel(LPC_DMA, DMA_CH0);
}

/* Clear DMA interrupt for the channel */
Chip_DMA_ClearActiveIntAChannel(LPC_DMA, DMA_CH0);
}

/***
* ____ __ __ _
* | _ \| \/ | / \
* | | | | |\/| | / _ \
* | |_| | | | |/ ___ \
* |____/|_| |_/_/ \_\
* / ___| ___| |_ _ _ _ __
* \___ \ / _ \ __| | | | '_ \
* ___) | __/ |_| |_| | |_) |
* |____/ \___|\__|\__,_| .__/
* |_|
*/
void DMA_Setup(void)
{
DMA_CHDESC_T Initial_DMA_Descriptor;

ADC_TransferDescriptors[0].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0];
ADC_TransferDescriptors[1].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0];
ADC_TransferDescriptors[2].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0];
ADC_TransferDescriptors[3].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0];

ADC_TransferDescriptors[0].dest = DMA_ADDR(&CapturedData[(0+1)*DMA_TRANSFER_SIZE-1]);
ADC_TransferDescriptors[1].dest = DMA_ADDR(&CapturedData[(1+1)*DMA_TRANSFER_SIZE-1]);
ADC_TransferDescriptors[2].dest = DMA_ADDR(&CapturedData[(2+1)*DMA_TRANSFER_SIZE-1]);
ADC_TransferDescriptors[3].dest = DMA_ADDR(&CapturedData[(3+1)*DMA_TRANSFER_SIZE-1]);

//The initial DMA desciptor is the same as the 1st transfer descriptor. It
//Will link into the 2nd of the main descriptors.

ADC_TransferDescriptors[0].next = (uint32_t)&ADC_TransferDescriptors[1];
ADC_TransferDescriptors[1].next = (uint32_t)&ADC_TransferDescriptors[2];
ADC_TransferDescriptors[2].next = (uint32_t)&ADC_TransferDescriptors[3];

//Link back to the 1st descriptor
ADC_TransferDescriptors[3].next = (uint32_t)&ADC_TransferDescriptors[0];

//For a test, stop the transfers here. The sine wave will look fine.
//ADC_TransferDescriptors[3].next = 0;

ADC_TransferDescriptors[1].xfercfg = ADC_TransferDescriptors[0].xfercfg;
ADC_TransferDescriptors[2].xfercfg = ADC_TransferDescriptors[0].xfercfg;

Initial_DMA_Descriptor.source = ADC_TransferDescriptors[0].source;
Initial_DMA_Descriptor.dest = ADC_TransferDescriptors[0].dest;
Initial_DMA_Descriptor.next = (uint32_t)&ADC_TransferDescriptors[1];
Initial_DMA_Descriptor.xfercfg = ADC_TransferDescriptors[0].xfercfg;

/* DMA initialization - enable DMA clocking and reset DMA if needed */
Chip_DMA_Init(LPC_DMA);

/* Enable DMA controller and use driver provided DMA table for current descriptors */
Chip_DMA_Enable(LPC_DMA);
Chip_DMA_SetSRAMBase(LPC_DMA, DMA_ADDR(Chip_DMA_Table));

/* Setup channel 0 for the following configuration:
- High channel priority
- Interrupt A fires on descriptor completion */
Chip_DMA_EnableChannel(LPC_DMA, DMA_CH0);
Chip_DMA_EnableIntChannel(LPC_DMA, DMA_CH0);
Chip_DMA_SetupChannelConfig(LPC_DMA, DMA_CH0, //(DMA_CFG_PERIPHREQEN |
(DMA_CFG_HWTRIGEN |
DMA_CFG_TRIGBURST_BURST |
DMA_CFG_TRIGTYPE_EDGE |
DMA_CFG_TRIGPOL_HIGH | //DMA_CFG_TRIGPOL_HIGH
DMA_CFG_BURSTPOWER_1 |
DMA_CFG_CHPRIORITY(0)
)
);

//make sure ADC Sequence A interrupts is selected for for a DMA trigger
Chip_INMUX_SetDMATrigger(DMA_CH0, DMATRIG_ADC0_SEQA_IRQ);

/* Enable DMA interrupt */
NVIC_EnableIRQ(DMA_IRQn);

// The 1st descriptor is set up through the registers.

/* Setup transfer descriptor and validate it */
Chip_DMA_SetupTranChannel(LPC_DMA, DMA_CH0, &Initial_DMA_Descriptor);

//Use the transfer configuration for our 4 main descriptors
Chip_DMA_SetupChannelTransfer(LPC_DMA, DMA_CH0, ADC_TransferDescriptors[0].xfercfg);
Chip_DMA_SetValidChannel(LPC_DMA, DMA_CH0);
}

void SCT_PWM_Generate(void)
{
/* Initialize the SCT2 as PWM and set frequency */
Chip_SCTPWM_Init(LPC_SCT2);
Chip_SCTPWM_SetRate(LPC_SCT2, SCT_PWM_RATE);

/* Use SCT2_OUT3 pin */
Chip_SCTPWM_SetOutPin(LPC_SCT2, SCT_PWM_OUT, SCT_PWM_PIN_OUT);

/* Start with 50% duty cycle */
Chip_SCTPWM_SetDutyCycle(LPC_SCT2, SCT_PWM_OUT, Chip_SCTPWM_PercentageToTicks(LPC_SCT2, 50));
Chip_SCTPWM_Start(LPC_SCT2);
}

/***
* _ ____ ____
* / \ | _ \ / ___|
* / _ \ | | | | |
* / ___ \| |_| | |___
* /_/__ \_\____/ \____|
* / ___| ___| |_ _ _ _ __
* \___ \ / _ \ __| | | | '_ \
* ___) | __/ |_| |_| | |_) |
* |____/ \___|\__|\__,_| .__/
* |_|
*/
void ADC_Setup(void)
{
/*Set Asynch Clock to the Main clock*/
// LPC_SYSCON->ADCCLKSEL = 0;
// Chip_Clock_SetADCASYNCSource(SYSCTL_ADCASYNCCLKSRC_IRC);
//Set the divider to 1 and enable. note, the HALT bit (30) and RESET (29) are not in the manual
// LPC_SYSCON->ADCCLKDIV = 0;

/* Initialization ADC to 12 bit and set clock divide to 1 to operate synchronously at System clock */
Chip_ADC_Init(LPC_ADC0, ADC_CR_BITACC(0) | ADC_CR_CLKDIV(0)| ADC_CR_ASYNMODE);
Chip_ADC_SetClockRate(LPC_ADC0, ADC_MAX_SAMPLE_RATE);
//select ADC Channel 0 as input
Chip_IOCON_PinMuxSet(LPC_IOCON, 0, 8, IOCON_FUNC0 | IOCON_MODE_INACT | IOCON_ADMODE_EN);
Chip_SWM_Init();
Chip_SWM_EnableFixedPin(SWM_FIXED_ADC0_0); //P0_8

Chip_ADC_SetADC0Input(LPC_ADC0, ADC_INSEL_ADC0);

//Setup ADC0_SEQA_IRQ
Chip_ADC_SetupSequencer(LPC_ADC0,ADC_SEQA_IDX,
ADC_SEQ_CTRL_SEQ_ENA |
ADC_SEQ_CTRL_CHANSEL(ADC_INPUT_CHANNEL) |
ADC0_SEQ_CTRL_HWTRIG_SCT2_OUT3 |
// ADC_SEQ_CTRL_HWTRIG_POLPOS |
// ADC_SEQ_CTRL_HWTRIG_SYNCBYPASS |
ADC_SEQ_CTRL_MODE_EOS);
/* Enable Sequence A interrupt */
Chip_ADC_EnableInt(LPC_ADC0, ADC_INTEN_SEQA_ENABLE);

/* Calibrate ADC */
Chip_ADC_StartCalibration(LPC_ADC0);
while (!(Chip_ADC_IsCalibrationDone(LPC_ADC0))) {}

Chip_ADC_ClearFlags(LPC_ADC0, Chip_ADC_GetFlags(LPC_ADC0));
// Chip_ADC_EnableInt(LPC_ADC0, ADC_INTEN_SEQA_ENABLE);
// NVIC_EnableIRQ(ADC0_SEQA_IRQn);
Chip_ADC_EnableSequencer(LPC_ADC0, ADC_SEQA_IDX);

}

int main(void)
{

/* Setup SystemCoreClock and any needed board code */
SystemCoreClockUpdate();
Board_Init();

DMA_Setup();
ADC_Setup();
SCT_PWM_Generate();

while(1)
{}
}

Re: LPC1549: How to use the DMA with the ADC

Alice_Yang — Wed, 20 Jan 2021 03:43:55 GMT

Hello Jesper,

“There are some ADC results in the buffer. But there are zeros and not completely processed data there too.”

-> Dose the data all right when only use ADC,without DMA?

Alice

Re: LPC1549: How to use the DMA with the ADC

jespermadsen — Wed, 20 Jan 2021 10:45:28 GMT

Hello Alice

If I keep a breakpoint in the loop and break it every time the interrupt fires, the value is not updated.

But if the MCU runs free for a while, and then I stop it, the value is correct.

Maybe the ADC interrupt is not correctly setup?

Best regards

Jesper

Re: LPC1549: How to use the DMA with the ADC

Alice_Yang — Thu, 21 Jan 2021 09:15:52 GMT

Hello,

"Maybe the ADC interrupt is not correctly setup?"

-> No, when you use breakpoint, there is some delay by software.

I recommend you set block to lock problem, for example without DMA, just check whether ADC

, then add DMA...

Re: LPC1549: How to use the DMA with the ADC

jespermadsen — Thu, 21 Jan 2021 11:48:53 GMT

Hello Alice.

Now the values comes into the buffer.. Thanks.

I removed the boardlib and made some small changes:

#include "chip.h" #include <cr_section_macros.h> #define NUM_BUFFERS 4 #define DMA_TRANSFER_SIZE 8 #define ADC_INPUT_CHANNEL 0 #define SCT_PWM_RATE 10000 /* PWM frequency 10 KHz */ #define SCT_PWM_PIN_OUT 3 /* COUT3 Generate square wave */ #define SCT_PWM_OUT 3 /* Index of OUT PWM */ uint16_t adcOut; DMA_CHDESC_T ADC_TransferDescriptors[NUM_BUFFERS] __attribute__ ((aligned(512))); uint16_t CapturedData[32]; uint16_t DMA_Sum=0; /** * * ADC IRQ not Used right now... Only for testing */ void ADC_SEQA_IRQHandler(void) { /* If SeqA flags is set i.e. data in global register is valid then read it */ Chip_ADC_ClearFlags(LPC_ADC0,0xFFFFFFFF); } void DMA_IRQHandler(void) { static uint16_t DMA_Sum=0; DMA_Sum++; if(DMA_Sum ==8) { DMA_Sum=4; } /* Error interrupt on channel 0? */ if ((Chip_DMA_GetIntStatus(LPC_DMA) & DMA_INTSTAT_ACTIVEERRINT) != 0) { /* This shouldn't happen for this simple DMA example, so set the LED to indicate an error occurred. This is the correct method to clear an abort. */ Chip_DMA_DisableChannel(LPC_DMA, DMA_CH0); while ((Chip_DMA_GetBusyChannels(LPC_DMA) & (1 << DMA_CH0)) != 0) {} Chip_DMA_AbortChannel(LPC_DMA, DMA_CH0); Chip_DMA_ClearErrorIntChannel(LPC_DMA, DMA_CH0); Chip_DMA_EnableChannel(LPC_DMA, DMA_CH0); } /* Clear DMA interrupt for the channel */ Chip_DMA_ClearActiveIntAChannel(LPC_DMA, DMA_CH0); } /*** * ____ __ __ _ * | _ \| \/ | / \ * | | | | |\/| | / _ \ * | |_| | | | |/ ___ \ * |____/|_| |_/_/ \_\ * / ___| ___| |_ _ _ _ __ * \___ \ / _ \ __| | | | '_ \ * ___) | __/ |_| |_| | |_) | * |____/ \___|\__|\__,_| .__/ * |_| */ void DMA_Setup(void) { DMA_CHDESC_T Initial_DMA_Descriptor; ADC_TransferDescriptors[0].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0]; ADC_TransferDescriptors[1].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0]; ADC_TransferDescriptors[2].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0]; ADC_TransferDescriptors[3].source = (uint32_t)&LPC_ADC0->SEQ_GDAT[0]; ADC_TransferDescriptors[0].dest = DMA_ADDR(&CapturedData[(0+1)*DMA_TRANSFER_SIZE-1]); ADC_TransferDescriptors[1].dest = DMA_ADDR(&CapturedData[(1+1)*DMA_TRANSFER_SIZE-1]); ADC_TransferDescriptors[2].dest = DMA_ADDR(&CapturedData[(2+1)*DMA_TRANSFER_SIZE-1]); ADC_TransferDescriptors[3].dest = DMA_ADDR(&CapturedData[(3+1)*DMA_TRANSFER_SIZE-1]); //The initial DMA desciptor is the same as the 1st transfer descriptor. It //Will link into the 2nd of the main descriptors. ADC_TransferDescriptors[0].next = (uint32_t)&ADC_TransferDescriptors[1]; ADC_TransferDescriptors[1].next = (uint32_t)&ADC_TransferDescriptors[2]; ADC_TransferDescriptors[2].next = (uint32_t)&ADC_TransferDescriptors[3]; //Link back to the 1st descriptor ADC_TransferDescriptors[3].next = (uint32_t)&ADC_TransferDescriptors[0]; //For a test, stop the transfers here. The sine wave will look fine. //ADC_TransferDescriptors[3].next = 0; ADC_TransferDescriptors[0].xfercfg = (DMA_XFERCFG_CFGVALID | DMA_XFERCFG_RELOAD | DMA_XFERCFG_SETINTA | DMA_XFERCFG_WIDTH_16 | DMA_XFERCFG_SRCINC_0 | DMA_XFERCFG_DSTINC_1 | DMA_XFERCFG_XFERCOUNT(DMA_TRANSFER_SIZE)); ADC_TransferDescriptors[1].xfercfg = ADC_TransferDescriptors[0].xfercfg; ADC_TransferDescriptors[2].xfercfg = ADC_TransferDescriptors[0].xfercfg; ADC_TransferDescriptors[3].xfercfg = (DMA_XFERCFG_CFGVALID | DMA_XFERCFG_RELOAD | DMA_XFERCFG_SETINTA | DMA_XFERCFG_WIDTH_16 | DMA_XFERCFG_SRCINC_0 | DMA_XFERCFG_DSTINC_1 | DMA_XFERCFG_XFERCOUNT(DMA_TRANSFER_SIZE)); Initial_DMA_Descriptor.source = ADC_TransferDescriptors[0].source; Initial_DMA_Descriptor.dest = ADC_TransferDescriptors[0].dest; Initial_DMA_Descriptor.next = (uint32_t)&ADC_TransferDescriptors[1]; Initial_DMA_Descriptor.xfercfg = ADC_TransferDescriptors[0].xfercfg; /* DMA initialization - enable DMA clocking and reset DMA if needed */ Chip_DMA_Init(LPC_DMA); /* Enable DMA controller and use driver provided DMA table for current descriptors */ Chip_DMA_Enable(LPC_DMA); Chip_DMA_SetSRAMBase(LPC_DMA, DMA_ADDR(Chip_DMA_Table)); /* Setup channel 0 for the following configuration: - High channel priority - Interrupt A fires on descriptor completion */ Chip_DMA_EnableChannel(LPC_DMA, DMA_CH0); Chip_DMA_EnableIntChannel(LPC_DMA, DMA_CH0); Chip_DMA_SetupChannelConfig(LPC_DMA, DMA_CH0, //(DMA_CFG_PERIPHREQEN | (DMA_CFG_HWTRIGEN | DMA_CFG_TRIGBURST_BURST | DMA_CFG_TRIGTYPE_EDGE | DMA_CFG_TRIGPOL_HIGH | //DMA_CFG_TRIGPOL_HIGH DMA_CFG_BURSTPOWER_1 | DMA_CFG_CHPRIORITY(0) ) ); //make sure ADC Sequence A interrupts is selected for for a DMA trigger Chip_INMUX_SetDMATrigger(DMA_CH0, DMATRIG_ADC0_SEQA_IRQ); /* Enable DMA interrupt */ NVIC_EnableIRQ(DMA_IRQn); // The 1st descriptor is set up through the registers. /* Setup transfer descriptor and validate it */ Chip_DMA_SetupTranChannel(LPC_DMA, DMA_CH0, &Initial_DMA_Descriptor); //Use the transfer configuration for our 4 main descriptors Chip_DMA_SetupChannelTransfer(LPC_DMA, DMA_CH0, ADC_TransferDescriptors[0].xfercfg); Chip_DMA_SetValidChannel(LPC_DMA, DMA_CH0); } void SCT_PWM_Generate(void) { /* Initialize the SCT2 as PWM and set frequency */ Chip_SCTPWM_Init(LPC_SCT2); Chip_SCTPWM_SetRate(LPC_SCT2, SCT_PWM_RATE); /* Use SCT2_OUT3 pin */ Chip_SCTPWM_SetOutPin(LPC_SCT2, SCT_PWM_OUT, SCT_PWM_PIN_OUT); /* Start with 50% duty cycle */ Chip_SCTPWM_SetDutyCycle(LPC_SCT2, SCT_PWM_OUT, Chip_SCTPWM_PercentageToTicks(LPC_SCT2, 50)); Chip_SCTPWM_Start(LPC_SCT2); } /*** * _ ____ ____ * / \ | _ \ / ___| * / _ \ | | | | | * / ___ \| |_| | |___ * /_/__ \_\____/ \____| * / ___| ___| |_ _ _ _ __ * \___ \ / _ \ __| | | | '_ \ * ___) | __/ |_| |_| | |_) | * |____/ \___|\__|\__,_| .__/ * |_| */ void ADC_Setup(void) { /* Initialization ADC to 12 bit and set clock divide to 1 to operate synchronously at System clock */ Chip_ADC_Init(LPC_ADC0, ADC_CR_BITACC(0) | ADC_CR_CLKDIV(0)| ADC_CR_ASYNMODE); Chip_ADC_SetClockRate(LPC_ADC0, ADC_MAX_SAMPLE_RATE); //select ADC Channel 0 as input Chip_IOCON_PinMuxSet(LPC_IOCON, 0, 8, IOCON_FUNC0 | IOCON_MODE_INACT | IOCON_ADMODE_EN); Chip_SWM_Init(); Chip_SWM_EnableFixedPin(SWM_FIXED_ADC0_0); //P0_8 Chip_ADC_SetADC0Input(LPC_ADC0, ADC_INSEL_ADC0); //Setup ADC0_SEQA_IRQ Chip_ADC_SetupSequencer(LPC_ADC0,ADC_SEQA_IDX, ADC_SEQ_CTRL_SEQ_ENA | ADC_SEQ_CTRL_CHANSEL(ADC_INPUT_CHANNEL) | ADC0_SEQ_CTRL_HWTRIG_SCT2_OUT3 | // ADC_SEQ_CTRL_HWTRIG_POLPOS | // ADC_SEQ_CTRL_HWTRIG_SYNCBYPASS | ADC_SEQ_CTRL_MODE_EOS); /* Enable Sequence A interrupt */ Chip_ADC_EnableInt(LPC_ADC0, ADC_INTEN_SEQA_ENABLE); /* Calibrate ADC */ Chip_ADC_SetTrim(LPC_ADC0, ADC_TRIM_VRANGE_HIGHV); Chip_ADC_StartCalibration(LPC_ADC0); while (!(Chip_ADC_IsCalibrationDone(LPC_ADC0))) {} Chip_ADC_ClearFlags(LPC_ADC0, Chip_ADC_GetFlags(LPC_ADC0)); // NVIC_EnableIRQ(ADC0_SEQA_IRQn); Chip_ADC_EnableSequencer(LPC_ADC0, ADC_SEQA_IDX); } int main(void) { // Read clock settings and update SystemCoreClock variable SystemCoreClockUpdate(); Chip_GPIO_Init(LPC_GPIO); Chip_GPIO_SetPinDIROutput(LPC_GPIO, 0, 0); DMA_Setup(); ADC_Setup(); SCT_PWM_Generate(); while(1) {} return 0 ; }

Re: LPC1549: How to use the DMA with the ADC

jespermadsen — Fri, 22 Jan 2021 13:05:44 GMT

There are still some problems in the program.

I tried to set it up with

DMA_TRANSFER_SIZE 64

SCT_PWM_RATE 5000

And a 70 Hz triangle signal on the ADC-input.

The samples with DMA are chopped as you see in the pictures

The samples without DMA has only one jump.

How can this be?

PS: The curves in the figurs are not in fase.

ADC-input:

Samples without DMA:

Samples with DMA: