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Can't read EDID using direct method on SN65DSI86

Victor Praxedes
Prodigy 70 points

Hello,

I'm having issues with the direct method for reading EDID. I can read and write the DSIX6 registers using i2c device address 0x58/0x59 just fine, but when i configure the 0x60 register (I2C_ADDR_CLAIM1) to 0x51 and try to read from address 0x50, it returns NACK and i see no signal on the AUX pins. Same thing happens if i write 0xA1 to the I2C_ADDR_CLAIM1 and try to read from 0x50, i see no activity on the AUX pins.

I'm also confused as why this example is using 0x2D as the device ID instead of 0x58 or 0x5A which are the 2 i2c addresses in section 8.5.1.

 Is there anything i'm missing?

  • 0
    Prodigy 70 points
    Oh, forgot to mention that using 0x2D as the device address also returns me NACK.
  • 0 in reply to Victor Praxedes
    TI__Mastermind 18655 points

    Hello Victor, 

    Does your I2C master support clock stretching?

    Regarding to the example, the slave address is 0x2D due to those scripts are for a Total Phase Aardvark I2C controller  so the slave address is specified as shown below.

    The first seven bits of the byte comprise the slave address. The eighth bit is the read/write flag where 0 indicates a write and 1 indicates a read.

    When ADDR=1, Address Cycle is 0x5A (Write) and 0x5B (Read)  (0x2D for 7 bit addressing )
    When ADDR=0, Address Cycle is 0x58 (Write) and 0x59 (Read)  

    In order to I2C Read of the EDID  software must do the following:

    1.- ======Enable I2C_ADDR_CLAIM1====== 
    <i2c_write addr="0x2D" count="1" radix="16">60 A1 />

    2.- ======Write EDID base of 00 ====== 
    <i2c_write addr="0x50" count="0" radix="16">00 /> 

    3.-======Read 256 bytes of EEID======
    <i2c_read addr="0x50" count="256" radix="16">00 />

    Regards,
    Joel 

  • 0 in reply to Joel Jimenez0
    Prodigy 70 points

    Hi Joel,

    I thought FT2232 on I2C mode supported clock stretching, but reading the fine print i found out that it doesn't! Guess i'll have to go with the indirect mode.

    Thank you!