TPS23881EVM-008: Having issue in reading data registers

Muhammad Ali Jayyad

Part Number: TPS23881EVM-008
Other Parts Discussed in Thread: TPS23881

Hi, its my first time with TPS23881 and I'm having trouble reading register data from TPS23881.

I'm using TPS23881EVM-008 with STM32 for a custom PoE switch application.

I have successfully loaded SRAM and Parity codes in TPS23881 and able to verify firmware version from register 0x41, which means my I2C is working fine and both devices are communicating. But I'm unable to read any other register, i always get 0x00.

Also im following steps in TI's example code.

11 months ago

+1 Brandon Beader 11 months ago

TI__Genius 14115 points

Hi Muhammad,

What mode are you operating in? After power up and successful SRAM loading, you need to set the device to an operating mode. I would recommend after loading your SRAM, you set the device to AUTO mode by writting to register 12h and 13h value of 0xFF. This will set all channels to AUTO mode. You can verify this write operation with a readback to the same register.

In AUTO mode, the device will do detection/classification automatically and turn on the port. This will also update associated registers.

Regards,

Brandon

0 Muhammad Ali Jayyad 11 months ago in reply to Brandon Beader

Prodigy 30 points

Thanks for your response,

I am using it in semi auto mode and now able to read 13h, previously I was not setting this register.

but still I'm not able to read back 12h, i I have set it to 0xAA for both device address 0x20 and 0x21 and when I try to read 12h back it returns 0x00

0 Brandon Beader 11 months ago in reply to Muhammad Ali Jayyad

TI__Genius 14115 points

Hi Muhammed,

Can you provide a full register dump so I can take a look at your settings?

Regards,

Brandon

+1 Muhammad Ali Jayyad 11 months ago in reply to Brandon Beader

Prodigy 30 points

Thanks Brandon for your help.

I got this issue resolved.

I missed some steps in configuring TPS23881 on power up.

Power management

Power management forum

TPS23881EVM-008: Having issue in reading data registers