ADC internal connection must be clarified among sources

[Yoichi Shinoda]

Different sources give different and/or ambiguous information on ADC internal connections.

Take VREFINT on G474 for example.

Datasheet (DS12288 Rev 1) Section 3.18.2 Internal voltage reference (VREFINT) say

• The VREFINT is internally connected to the ADCx_IN18, x = 1,3,4,5 input channel.

Reference manual (RM0440 Rev 1) Section 20.4.33 Monitoring the internal voltage reference say

• The internal voltage reference is internally connected to the input channel 0 of the ADC1 (ADC1_INP0).

FW1.0.0 stm32g4xx_hal_adc.h suggest

• ADC internal channel connected to VrefInt: Internal voltage reference. On this STM32 serie, ADC channel available on all instances but ADC2.
• (Which is essentially saying the same as the data sheet.)

Similar confusion on internal temperature sensor. In this case, FW1.0.0 stm32g4xx_hal_adc.h is saying two different things in comments for channel identifiers.

• ADC internal channel connected to Temperature sensor. On this STM32 serie, ADC channel available only on ADC1 instance.
• ADC internal channel connected to Temperature sensor. On this STM32 serie, ADC channel available only on ADC5 instance. Refer to device datasheet for ADC5 availaibility.

It is unclear which connection(s) are actually connected for devices with ADC1 and ADC5.

[Mike_ST]

Dear Yoichi,

I think you are refering to RM0440 "20.4.33 Monitoring the internal voltage reference". As you guessed it, ADC1_INP0 is not correct.

I raised a ticket for that.

Related to VREFINT, as you mentionned, it is available on ADCx_IN18, x = 1,3,4,5 input channels.

Related to Temperature Sensing, it is available on both, ADC1 Channel 16, and ADC5 channel 4, for devices with ADC1 and ADC5.