DS90UB901Q - reading address problem

Karel Roubik

Can you please help with the following problem?
When transmitting command to a slave address (read register) is not transfer bit 0 (read flag). 
To deserializer is sent the address with this bit set (odd number) and 
the serializer send command to slave device with this bit reset to zero. 
(I use the Index ID1 and ID1 Match registers. Values 0x42=camera slave address, 0x82=my reading channel )
Thank very much.

over 10 years ago

0 Dac Tran over 10 years ago

TI__Expert 7395 points

Hi Karel,

Based on the camera/display operating mode, please follow the steps described in the 901/902 EVM user’s guide on pages 20-27 -- http://www.ti.com/lit/ug/snlu100/snlu100.pdf

Dac Tran

SVA APPS

0 Karel Roubik over 10 years ago in reply to Dac Tran

Prodigy 30 points

Hi Dac,
Thank you for answer. The recommended procedure I performed several times, unfortunately, still with the same result. The only thing I changed is the address of the camera, which in my case 0x42, respectively. 0x43 for read. (camera Ov7725)
I send to You by email code listing, which I test and a picture from oscilloscope that demonstrates the problem.

Thanks

Karel

0 Dac Tran over 10 years ago in reply to Karel Roubik

TI__Expert 7395 points

Hi Karel,

It is not necessary to specify the read bit flag (bit 0) when executing an I2C read command on the 902. The internal 901/902 I2C controller engine will handle the read/write operations. You should only program 0x42 on both 902 reg0x08 and reg0x10.

Dac Tran

SVA APPS

0 Karel Roubik over 10 years ago in reply to Dac Tran

Prodigy 30 points

Hi Dac

Thank you for your help. It turned out that the problem was elsewhere. Bit 0 was pulled to L by the camera.

Best regards,

Karel

Interface

Interface forum

DS90UB901Q - reading address problem