Tool/software:
Hi champs,
I am asking this for our customer.
In TRM,
14.12.1 Ensuring Synchronous Operation
We need to sync between ADC modules.
The user also needs to use ADC oversampling by PPB, do they need to consider them both?
If yes, how do they handle both ADC module sync and HW oversampling?
Would you please show us an example explicitly?
For example,
In ADC A and ADC B, they use SOC0-5.
In ADC C, they user SOC0 for oversampling.
How should they do?
Hello Wayne,
In sync operation, all ADC should have the same sampling time and conversion time. This means that all the ADCs are operating at the same speed. Basic representation of this synchronized conversion is given below:
Easiest way to attain synchronized conversion would be to:
- Ensure all ADCs use the same clock prescaler so that they operate at the same frequency
- Use the same ACQPS for all the ADCs - this will ensure that the green regions (sampling) in the above diagram do not overlap. Blue regions (conversion) will not overlap as long as ADC operate at the same speed (first requirement)
- Trigger all conversions at the same time. This can be accomplished by using same trigger source for all ADCs, for example use EPWM1 to generate SOCA and use EPWM1 SOCA as trigger source for all the ADCs/SOCs.
HW oversampling uses the same timing as normal ADC conversion. In HW oversampling, the repeater block is just performing basic ADC conversion (sampling->conversion) for a number of times specified by the repeater. If EPWM1 SOCA is used as the trigger source, just ensure that EPWM1 SOCA period is longer than the total conversion sequence x number of repeats to ensure that ADCC completes the HW oversampling before ADCA and ADCB gets triggered again by the next SOCA trigger.
Regards,
Joseph
