Compatibility between pin functions

[Nadia]

Hello to all. I am using a LPC54616J, and I encountered a problem with the ADC. I have seen that it only has 8 ADC inputs, and that two of them are used for programming the MCU. Does anyone know if the programming inputs, corresponding to pins 24 and 25 of the MCU, could be used to input analogue signals through them?

I haven't found anything in the Datasheet about the compatibility of functions of the pins, as each pin can be used for several functions.

Thank you very much.

[PabloAvalos]

Hi, @Nadia

Hoping you are well.

I would like to say that pins 24 and 25 are not specified in the datasheet as ADC inputs as an alternative functionality as you mentioned, so that means that those pins cannot be used for this purpose. Therefore, you can check the datasheet for your specific mcu and package here LPC546XX Datasheet where you will be able to check which pins are specified as ADC inputs.

Regarding your part number, I would like to know which is your full part number and the type of package, so I can help you more personalizedly.

Sincerely,

Pablo Avalos.

[frank_m]

> I haven't found anything in the Datasheet about the compatibility of functions of the pins, as each pin can be used for several functions.

In basically all cases, you can use one out of <n> possible functions.

I don't know the LPC54616J in detail, but if you need more ADC inputs, I would recommend another version with different pinout/more pins, or another MCU, or an external ADC.

> Does anyone know if the programming inputs, corresponding to pins 24 and 25 of the MCU, could be used to input analogue signals through them?

In theory, you can configure these pins as ADC inputs during startup.

But not only will you probably need jumpers (possible interference between programming and ADC functionality), but also lose debugging capabilitites. The JTAG/SWD is both programming and debugging interface. And forgoing the capability to debug hardly ever played out well.

[Nadia]

But I can use the programming inputs as ADC signal receiver ports without any problem?

[frank_m]

You would need to check with the datasheet/manual, but if it says so, yes.

However, you need to make sure that your ADC interface wiring does not interfere with with programming, and the programming interface wiring does not interfere with the ADC functionality.

Dropping the debug interface for the sake of BOM costs is usually a decision inexperienced developers make, through pressure by technically unaware project managment. Usually followed by an epic nosedive.

This is my experience.