About nRF52xx ADC stability issues

Gen_X

About nRF52xx ADC stability issues [Copy link]

Hello everyone, has anyone used the ADC of nRF52811/32?

It was found that there was mutual interference between communication and ADC. Has anyone used timed interruption to collect and send data?

Is it necessary to strictly avoid the interval between ADC and transmission and reception in terms of timing? What is the minimum time for this interval?

tagetage

The mutual interference between communication and ADC is usually caused by power-related problems. Is your device powered by a battery? Please observe whether the power supply fluctuates during ADC sampling and chip transmission and reception. Generally, the ADC is performed during the transmission period. Generally, the transmission can be performed after the ADC sampling value is read.

chunyang

The ADC itself will not interfere with other circuits in the chip, otherwise there will be serious problems in the chip design. This is logic. When this phenomenon occurs, the problem should be found from the forward channel of the ADC. It is speculated that the input signal causes coupling interference to the reception, which is related to the circuit/PCB design. Another possibility is that there is no interference problem at all, but the software process is improperly designed, and it is the "interference" caused by the software, then the process should be optimized.

Gen_X

tagetage posted on 2022-3-10 10:51 Mutual interference between communication and ADC is generally caused by power-related problems. Is your device battery-powered? During ADC sampling and during chip transmission and reception...

@tagetage’s analysis is correct! Thanks for the reminder.

It is indeed powered by batteries, and the problem is solved after the power capacitor is increased to 470uF. After all, the transmission is not continuous.

Of course, this problem can be solved by software delay, but it takes 5-10mS, which causes time resource problems. Battery-powered devices also need to strictly manage time in order to increase necessary sleep and save power consumption.

wangerxian

It should be that during transmission, the power consumption suddenly increased, causing the battery to have a voltage drop, which in turn caused the voltage collected by the ADC to drift.