ADC DMA

Vijayanarayana R

Dear All

I am trying to get data from an RGB sensor and transfer the same to UART for Processing in the GUI, I am triggering the ADC by PWM which is about 500Khz

My Plan is to do a DMA transfer from the ADC0 FIFO to a Array and then to the Serial Port

how ever i am unable to get the data from the FIFO to the ARRAY here is the code for the same pls correct me if i have gone wrong some where

///////////////ADC Configuration for A0,A1,A2/////////////////////
ADCClockConfigSet(ADC0_BASE, ADC_CLOCK_SRC_PIOSC | ADC_CLOCK_RATE_FULL, 1);
ADCSequenceConfigure(ADC0_BASE,1,ADC_TRIGGER_PWM_MOD0|ADC_TRIGGER_PWM1, 0);
ADCSequenceStepConfigure(ADC0_BASE, 1, 0, ADC_CTL_CH0);
ADCSequenceStepConfigure(ADC0_BASE, 1, 1, ADC_CTL_CH1);
ADCSequenceStepConfigure(ADC0_BASE, 1, 2, ADC_CTL_CH2 | ADC_CTL_IE | ADC_CTL_END);
ADCSequenceEnable(ADC0_BASE, 1);
ADCIntClear(ADC0_BASE, 1);
ADCIntEnable(ADC0_BASE, 1);

//////////////////////////uDMA Enable for ADC Values

uDMAEnable();
uDMAControlBaseSet(udmaCtrlTable);
ADCSequenceDMAEnable(ADC0_BASE,1);
uDMAChannelAttributeDisable(UDMA_CHANNEL_ADC0, UDMA_ATTR_ALTSELECT | UDMA_ATTR_HIGH_PRIORITY | UDMA_ATTR_REQMASK);
uDMAChannelAttributeEnable(UDMA_CHANNEL_ADC0, UDMA_ATTR_USEBURST);
uDMAChannelControlSet(UDMA_CHANNEL_ADC0 | UDMA_PRI_SELECT, UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1024);
uDMAChannelControlSet(UDMA_CHANNEL_ADC0 | UDMA_ALT_SELECT, UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1024);
uDMAChannelTransferSet(UDMA_CHANNEL_ADC0 | UDMA_PRI_SELECT, UDMA_MODE_PINGPONG, (void *)(ADC0_BASE + ADC_O_SSFIFO0), &Receive_Buff, ADC_SAMPLE_BUF_SIZE);
uDMAChannelTransferSet(UDMA_CHANNEL_ADC0 | UDMA_ALT_SELECT, UDMA_MODE_PINGPONG, (void *)(ADC0_BASE + ADC_O_SSFIFO0), &Receive_Buff, ADC_SAMPLE_BUF_SIZE);
uDMAChannelEnable(UDMA_CHANNEL_ADC0);
ADCIntEnable(ADC0_BASE, 1);

over 9 years ago

0 Amit Ashara over 9 years ago

TI__Guru**** 244440 points

Hello Vijay,

How are you sure that the ADC is performing the conversion in the first place so that a DMA request can be asserted to transfer the data from the FIFO?

0 Vijayanarayana R over 9 years ago in reply to Amit Ashara

Prodigy 160 points

Before implementing the DMA i was trying to transfer the data to the array and i was able to get the reading properly , and have sent it out to the UART as well but how ever the data that i receive is some what on the slower side

0 Amit Ashara over 9 years ago in reply to Vijayanarayana R

TI__Guru**** 244440 points

Hello Vijay

And the ADC conversion was with the PWM trigger and not Processor Trigger?

0 Vijayanarayana R over 9 years ago in reply to Amit Ashara

Prodigy 160 points

Hi Amit Ashara

Yes the ADC trigger was with the PWM trigger not the processor trigger

with regards

Vijay

Feathers India

0 Amit Ashara over 9 years ago in reply to Vijayanarayana R

TI__Guru**** 244440 points

Hello Vijay,

OK. The first thing to try is to remove UDMA_ARB_1024 and replace it with UDMA_ARB_1 to transfer 1 conversion at a time. The next thing when performing the debug is to provide a fixed value on the ADC pins and check if the SRAM is getting updated by the digital converted values. This will help us identify if the ADC conversion is working or not?

Also how are you mapping the Sample Sequence-1 to the DMA? I think the UDMA_CHANNEL_ADC0 is not the correct define to use. Please check the udma.h file for ADC0SS1 define.

0 Vijayanarayana R over 9 years ago in reply to Amit Ashara

Prodigy 160 points

Hi Amith

I have checked the ADC with a single conversion with PWM trigger as well the value is updating in the ADCFIFO register and i am getting the ADC conversion complete interrupt as well ,

Yes i have changed the UDMA_CHANNEL_ADC1 so that i can trigger the ADC sample sequencer 1 ,

My doubt is if i am selecting the channel in the following line but the SFR is not getting updated kindly clarify

uDMAChannelAssign(UDMA_CH15_ADC0_1);
uDMAChannelEnable(UDMA_CHANNEL_ADC1);

my guess is UDMA_CH15_ADC0_1 is for selecting the ADC0 sample sequencer 1 , which i have got it from udma.h file

0 Amit Ashara over 9 years ago in reply to Vijayanarayana R

TI__Guru**** 244440 points

Hello Vijaya

The correct define to use is UDMA_CH15_ADC0_1 for all places where UDMA_CHANNEL_ADC1 needs to be used.

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ADC DMA