I thought of a problem with BlueNRG-1 ADC measuring power supply voltage

cruelfox

I thought of a problem with BlueNRG-1 ADC measuring power supply voltage [Copy link]

 The power supply voltage is measured directly using ADC and calculated as follows: This is the VREF problem. The formula uses 2.4V, so I substituted it in and calculated it. The result is quite good at 3V. But when the power supply voltage drops to 2.4V or even lower, the result will be affected... VREF cannot have a voltage of 2.4V. I haven't tested how much the error is, but I just thought about this problem, and the challenge program doesn't deal with it.

littleshrimp

The reference source can be set to 0.6V xADC_InitType.ADC_ReferenceVoltage = ADC_ReferenceVoltage_0V6;

led2015

Is this voltage within the range?

cruelfox

littleshrimp posted on 2018-1-29 16:52 You can set the reference source to 0.6V xADC_InitType.ADC_ReferenceVoltage = ADC_ReferenceVoltage_0V6;

I did it this way. In ADC_Init(), it is handled like this /* Set the reference voltage */ ADC->CONF_b.REFSEL = ADC_InitStruct->ADC_ReferenceVoltage; The 0.6V corresponds to REFSEL, as shown in the manual screenshot above, Vbias is selected. Do not modify the 2.4V

littleshrimp

cruelfox posted on 2018-1-29 23:09 I did it this way. In ADC_Init(), it is handled like this /* Set the reference voltage */ ...

It is indeed like what you said, 0.6v corresponds to Vbias. I just tried it with an adjustable power supply with 1.5V, 1.6V and 1.8V. The result calculated by ADC is consistent with the actual voltage. According to the data sheet, the VDDA of ADC should support an input range of 1.7v~3.6V. I haven't found any corresponding information on how to implement it in practice