Servers by jDrones

PPM MEGA32U Chip Replacement for Ardupilot V2.4.1


(Adam Goldenstein) #1

I have an Ardupilot V2.4.1 board. Inputs IN4/5/6 don’t work and there is a defect on the top of the MEGA32U PPM chip that indicates its fried. Everything else seems to work. The top of the chip reads:

(ATMEL logo)

MEGA32u2

10268 TH

OF4378

I can’t find an exact replacement chip. Does anyone know if one of there will work or where to get a suitable replacement? https://www.digikey.com/products/en?KeyWords=mega32u2&WT.z_header=search_go&v=313&v=453&v=427&v=8025&v=1288&v=464&v=1289&v=580&v=463&v=150

I’m planing on replacing with a hot air rework gun. I’m good with small fiddly things like this but have never redone an SMD component like this or used a rework gun. Let me know if you have tried and its not feasible.

I’m wondering if I would be better off getting a 2.6 or 2.8 board. I’m not wanting to dump a bunch more money into this now our I’d get something else.


(jpkh) #2

Hi Adam,

Reworking your old board is fully feasible but I would not bother to fix old APMxx board anymore nor buy 2.6 or 2.8. Support for all APMxx boards has been dropped many years (2015) ago due limitations of the main controller. Latest software that you can get for old APMx boards is 3.2.1 (Copter). While latest beta release is 3.6-rc11 that runs on all current day boards.

http://ardupilot.org/copter/docs/common-apm25-and-26-overview.html

About your board version. Are you really sure that it is APM 2.4.1 ?!? When we worked with APM boards, real versions were APM2.0 and then APM2.5 / 2.6. APM2.8 is random Chinese version and never originated from ArduPilot group.

Nowdays ArduPilot supports many great boards. You could look one of those as theree are a lot of good replacement boards starting from small Omnibus boards to the bigger Pixhawk families. MatekF405-Wing is one great board if you want to do some cable soldering etc.

Sure for fun and practice, you can change old PPM encoder chip on your APM board. Chip is ATMEGA32U2-MU

Digikey link to correct IC:
https://www.digikey.com/product-detail/en/microchip-technology/ATMEGA32U2-MU/ATMEGA32U2-MU-ND/2050822

Here’s old programming guide for it:
http://ardupilot.org/copter/docs/common-ppm-encoder-apm2x-atmega32u2.html

Another possibility is to use external PPM encoder or a receiver that has PPM output. Not sure what firmware you have inside your but if you upgrade it to be latest ppm encoder firmware then you can use PPM input directly.

You short input’s 2-3 and then input 1 becomes as PPM input. Here’s doc to show PPM mode:
http://ardupilot.org/copter/docs/common-connecting-the-radio-receiver-apm2.html

Have fun…