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FM430 - I2C Connection

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FM430 - I2C Connection

Postby applewood » Thu Jul 10, 2008 5:42 am

We are connecting our Clyde Space power system to our FM430 and attempting to read some battery data as part of testing the I2C data pathway. We have based the sample program on one obtained from the TI's slac015l I2C sample programs.

Everything compiles and seems to run well up to the point where the program is waiting to receive data from the CS board. One of the possible reasons for this problem would be an incorrect slave address. In the Clyde Space CubeSat Power System User Manual CS states that "All commands start with the 7 bit slave address (Default decimal 1)…"

Our questions:

1. Does the FM430 recognize this 0x01 slave address or does it set another slave address automatically?

2. Is there some way to verify the slave address?

Thank You

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Re: FM430 - I2C Connection

Postby aek » Thu Jul 10, 2008 10:26 am

1) Yes, Clyde have told me that the EPS address is 0x01. Apparently this is a reserved I2C address, so this _may_ be an issue, but I doubt it.

2) Have you reviewed the I2C memo in the CSK Customer Download area?

3) We have not yet done any I2C work in-house, so I can't comment further on it.

4) I have _heard_ that people have had problems with the TI sample code.

5) Do you have an I2C analyzer? The Total Phase stuff is pretty inexpensive ...

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Re: FM430 - I2C Connection

Postby Kevin@ClydeSpace » Tue Aug 05, 2008 1:05 am

Morning,

0x01 is the I2C address for the EPS.

If you are still having communication issues with our EPS, please feel free to contact us.

Regards,

Kevin

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Re: FM430 - I2C Connection

Postby aek » Mon Aug 11, 2008 9:16 am

Your analysis is correct, and you need to review the I2C memo in the Customer Download area that explains how to conect P3.1 & P3.3 to SDA_SYS and SCL_SYS.

Take a look at the PCA9515A (TI or Philips) -- that's an even better solution to what I propose in the I2C memo.

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Re: FM430 - I2C Connection

Postby applewood » Mon Aug 11, 2008 10:32 am

It is our understanding that the CS Board does not have any connections to P3.1 and P3.3 for I2C data. Rather their I2C flows through the SDA_SYS and SCL_SYS pins (H1 41 and H1 43 respectively).

As the SDA_SYS and SCL_SYS pins are the only apparent connection for the I2C data from the CS Board to the Rev. C FM430, does that require us to read this data using those pins? If so, how do we configure them? That is, is there some expression analogous to P3SEL=0x0A for the SDA_SYS and SCL_SYS pins?

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Re: FM430 - I2C Connection

Postby Kevin@ClydeSpace » Thu Aug 14, 2008 1:32 am

Morning,

On the EPS there exists a user optional connection that will simply join P3.1 and P3.3 to SDA_SYS and SCL_SYS. This can be done in the field. Please contact us for further information about this.

Kevin

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Re: FM430 - I2C Connection

Postby aek » Thu Aug 14, 2008 3:46 am

quote:
On the EPS there exists a user optional connection that will simply join P3.1 and P3.3 to SDA_SYS and SCL_SYS. This can be done in the field. Please contact us for further information about this.
That is a viable option only if you have no plans to use SPI (e.g. the SD Card) within your CubeSat Kit. See the I2C memo for the reason(s) why.

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