ADC Hardware Trigger on P1.27 (falling edge) not working on LPC1768 hardware

[AkshayNaik1907]

Hello,

I am trying to test ADC hardware triggering on the LPC1768 using P1.27 as the trigger source with falling edge detection. In simulation, the ADC starts conversion correctly when I generate a falling edge on P1.27 , but on the actual hardware the ADC does not start conversion.

My ADC is configured for hardware trigger on P1.27 with falling edge, channels are enabled, and the ADC is powered.

I would like to know are there any limitations related to using P1.27 as an ADC trigger on LPC1768 hardware?

Any clarification or guidance will be greatly appreciated.

Thank you.

[Harry_Zhang · Accepted solution]

Hi @AkshayNaik1907 

yes—there’s a known errata on LPC176x that affects using P1.27 as the ADC external trigger. On real hardware the ADC can miss edges on P1.27 (and P2.10), so conversions don’t start reliably even though a simulator shows them working. The miss rate depends on the ADC peripheral clock.

You can refer to the errta

ES_LPC176x Errata sheet

BR

Harry