slave not responding

[jagannathan GOPALAKRISHNAN]

we are using max30205 for temp monitoring.  the slave is not responding pls. help.

[haakonsh]

The videos are not really giving me any information, I suggest you get access to a digital analyzer like the Saleae Logic Pro 8/16. It will translate the TWI communication into an easily readable form. 

Your packet format is wrong, you're missing the 'pointer' byte. See Figure 3.a in https://datasheets.maximintegrated.com/en/ds/MAX30205.pdf. 

Also you should not assume that 'm_set_mode_done' is true after a completed TWI transfer, you should verify by reading back the register value before setting the m_set_mode_done flag. Although the TWI bus relies on ACKs from the slave, it does not verify that the slave has received and responded to the data in the way that you want it to, it only ACKs when a byte has been successfully received. 

 

PS:
Thanks for sharing a project that compiles out of the box <3

[Manoj Hiwarkar]

But we have sent the pointer byte in the code. Do you have the code for the same.If you have then can you please upload it. ?

[haakonsh]

ahh never mind, I see you follow Fig 4.(b) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FOR 2-BYTE REGISTER SUCH AS TEMPERATURE, TOS, AND THYST. 

The only thing I can comment is that the length should be 4 and not 10. 

 

[Manoj Hiwarkar]

We tried with sizeof operator also. Can you please upload the code. Because we have to resolve this urgently. 

[haakonsh]

Have you tried using 4 as length parameter?

[Manoj Hiwarkar]

Our receive buffer array length is 11 bytes. So ,if i put 4 as length, then code will go to the hard fault handler.