Hey guys,
I am currently working with an ArduPilot Mega 2.5 to create an autonomous ground vehicle. I've been having trouble with reading the Eagle File and relating it to the chip layout. I am trying to connect a MLX90 series thermal sensor to the APM 2.5. From looking at the Eagle file, I know that SDA/SDL are digital pins 20/21 respectively but my problem is that I can't relate the digital pins to the actual pins on the board. Could someone explain to me how to find the correct pins as they don't align?
For example: on the APM 2.5 board, Output 1 signal pin is digital pin 12.
There seems to be no strategy in determining these pins. If anyone could help in telling me how to read the Eagle files and relating it to the Input,Output, Analog layout on the board to determine the digital pin OR just tell me where the SDA/SCL pins are... that'd be greatly appreciated.
Replies
Hi Brian,
I am currently trying to achieve the exact same goal as you did a year ago. For an academic experiment, I am trying to get this MLX90 sensor to talk to my APM board and send the data over the 3dr radio to my groundstation.
I think I got the connections figured out (my APM board has a dedicated I2C port for these things) but I was wondering if you got the code to work on your APM.
Any help would be greatly appreciated.
Hi,
Those schematics are not too good....
But one can see this:
The 8 PWM inputs go to PB0...PB7 on the ATMEGAU8 in the obvious order PWM1->PB0, ...., PWM8->BP7. If SJ2 is set opposite the default way, the so called CH5 signal (is that the same as IN5?) is connected to ATMEGA2560 instead of the output of the ATMEGAU8's PPM encoding.
The first 8 PWM outputs come from the ATMEGA2560, an a funny order. The details are clear enough both from the schematic and from the RCOutput_APM2.cpp file.
Then there are the 12 rows of pins at the side of the board, labeled A0...A11. A0...A7 are going to Port F on ATMEGA2560 in the logical order. A8 goes to PK0. A10, A11 and A12 are selectable:
Pin jumper opt1 opt2
A10 SJ103 PB7 PK1
A11 SJ102 PL4 PK2
A12 SJ101 PL5 PK3
where the first option is some digital IO pin and the other is analog in.
It's better to skip the Arduino pin (digital pin 27 etc.) numbers when analyzing, they only make things more difficult. |If you have to translate between Arduino and real world pins, look at the pins_arduino_mega.c file in libraries.
When I look at my old APM2.0 from the bottom, there are 2 solder pads named SDA and SCL. They are 3.3V level though - try find the PCA9306DC level converter on the schematic (far right) and the JP9 connector (bigh block center bottom) and you will know.
Regards
Soren
Hello, can you help me what are the digital input pins on the ardupilot 2.5 and their code numbers or how to figure it out from the pins_arduino_mega.c file like you said above?
@Mihai,
Try here: Pin-outs
Regards,
TCIII ArduRover2 Developer
@Brian,
This will help you with the APM2.5 pin assignments: http://code.google.com/p/ardupilot-mega/wiki/APM25board
This will help you with the I2C pin assignments even though they are for the magnetometer: http://code.google.com/p/ardupilot-mega/wiki/MagAPM2
Hope this helps.
You might want to join my ArduRover User Group to get specialized help with your rover project.
Regards,
TCIII