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Postby Albert » Tue Nov 03, 2009 2:50 am

I am trying to communicate via I2C from the MB to the EPS (Rev D). I know that ON_I2C must be activated and I can sense I2C signals at SDA_SYS and SCL_SYS.

Since I can't receive any answer from the EPS, I am not sure if the EPS microcontroller is running any code or not. Could you tell me if the EPS provided from Pumpkin runs any code that uses I2C? If not, where could I get the program that provides the I2C communications?


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Re: EPS Rev D

Postby aek » Tue Nov 03, 2009 8:21 am

Hi Albert.

As a Linear EPS user, you have schematics (705-00337D.PDF) and firmware (in cubesatkit software installer) available to you.

I2C on the Linear EPS is a planned future enhancement. It has not yet been implemented. The code that currently runs on the Linear EPS handles charging, discharging and status indications, but does not include any I2C operation. The processor used on the Linear EPS (MSP430F169) supports I2C.

If you'd like to add I2C to the Linear EPS, only R65 & R71 should be fitted in the "I2C Isolator" shown on page 4 of the schematics. This assumes that you are driving SCL_SYS and SDA_SYS from elsewhere in your system (e.g. via Rev D hardware). Then, you need to add your I2C code to the Linear EPS code. Finally, you'll need to pay close attention to the '16x errata, as the '16x series has many I2C errata.

Pumpkin does not currently provide any MSP439 I2C code. There are examples of I2C code available on the web (e.g. from TI or from the Yahoo! MSP430 group).

The MSP430 on the Linear EPS can be reprogrammed via the same JFPC-MSP430 that is used to (re)program an FM430 Flight Module or a Pluggable Processor Module (PPM) A1/A2/A3.

The Linear EPS code has options (see main.h) to enable debug output via the debug I/O panel of CrossWorks. This is useful when getting to know the Linear EPS code. It must be disabled for standalone operation.


[This message has been edited by aek (edited November 03, 2009).]

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