ADS1299 and PIC32MX250F128B Pins

hetelek · February 2016

Hi,

I am very new to Arduino and hardware in general. I have a fair amount of software experience, and I am trying to understand how the hardware/software work together in my OpenBCI 32 bit board.

I am slowly beginning to understand it, but I am having trouble understanding how the pins are connected to each other between the ADS1299 and PIC32MX250F128B chips. I think if I understand one of the pins, then I'll understand them all. I am first trying to understand the data ready digital output from the ADS1299 to the PIC.

In the documentation of the ADS1299 (page 9), it states DRDY is on terminal 47 (please excuse my vocabulary usage, I'm very new to all this!). I opened the design file of the 32 bit board in DesignSpark and saw that the ADS's terminal 47 is connected to the PIC's pin 2. The documentation on the PIC (page 4) states that pin 2 is 'RA0'.

My question here is how would you actually go about checking if the data ready is HIGH or LOW with software? I understand the very basic ideas of how it works, but it doesn't seem to be matching up. In the definitions file (line 14), it says the ADS's DRDY is on pin 9. Why? Why wouldn't it be pin 2 considering that's the pin that it's going into on the PIC.

Thank you for any help!

EDIT: I see that the PIC seems to have some funky thing going on with peripheral pin selection (page 129, section 11.3 in documentation). Could someone please try and simplify how this works if it's related to what I'm trying to understand? Thanks again.

hetelek · February 2016

Finally figured it out. I'm still not 100% where it can be found in the documentation (or if it can be), but the schematic design file has the physical/software pins mapped out. If you go to the PIC32MX250F128B chip in the bottom right corner, you will see the pins and there corresponding software pin numbers. For example, DRDY is physical pin 2 and software pin number 9 (which you can figure out by removing the prefix 'D' from 'D9').

I know this may have been an extremely basic question, but I hope someone finds it useful.

biomurph · February 2016

The OpenBCI on-board PIC is bootloaded with a customized ChipKIT core. We started with DP32

http://store.digilentinc.com/chipkit-dp32-dip-package-prototyping-microcontroller-board/

That link will take you to further documentation.

ADS1299 and PIC32MX250F128B Pins

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