Missing ADC burst sequence interrupt on LPC1125

[northtommy]

Hi,

I'm using LPC1125 with two sequences. Seq A with some channels in single shot mode. Seq B with some channels in burst mode. Both SEQx_INT enabled und EOS (end of sequence) set. The sequences are exclusivly used - so far so good.

Unfortuntely there are circumstances when switching from sequence A to B no Interrupt-Flags of B are set.

What I do during init:

Chip_ADC_Init(...)

Chip_ADC_SetClockRate(...)

Setting Pins for ADC usage...

Chip_ADC_DisableSequencer(LPC_ADC, ADC_SEQA_IDX);

Chip_ADC_DisableSequencer(LPC_ADC, ADC_SEQB_IDX);

Chip_ADC_SetupSequencer(LPC_ADC, ADC_SEQA_IDX, .... | MODE_EOS);

Chip_ADC_SetupSequencer(LPC_ADC, ADC_SEQB_IDX, .... | BURST | MODE_EOS);

Chip_ADC_EnableInt(LPC_ADC, ADC_INTEN_SEQA_ENABLE | ADC_INTEN_SEQB_ENABLE);

Chip_ADC_EnableSequencer(LPC_ADC, ADC_SEQA_IDX);

Chip_ADC_EnableSequencer(LPC_ADC, ADC_SEQB_IDX);

// Note! I use the Interrupt flags only for polling if a sequence is finished - no expectation to call the ISR - no enable in NVIC

What I do during switch sequence:

Chip_ADC_ClearFlags(LPC_ADC, 0xffffffff);

Chip_ADC_StartBurstSequencer(LPC_ADC, ADC_SEQB_IDX);

If I do this it does NOT work (no sequence Interrupt flags set in burst mode), except walking through Debugger during switch. Interrupt flags are set in this case in burst mode.

If I do this:

Chip_ADC_ClearFlags(LPC_ADC, 0xffffffff);

for ( int i = 0; i < 1000; i++) { j++; j = LPC_ADC->Flags; }

Chip_ADC_StartBurstSequencer(LPC_ADC, ADC_SEQB_IDX);

it works. Same Problem when disable/enable sequencer inbetween. Are there any non documented reads/writes or order of Setting bits in control Registers?

No notes in errata available...

Thx, Thomas

[jeremyzhou]

Hi Thomas,

According to the description, it seems that the ADC operation needs to add a delay time between the flag clearing execution and starting conversion sequences.

I was wondering if you can show me the more testing result to verify the assumption, then I can report the "issue" to AE for checking.
Have a great day,
Ping

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