Re: Trying to hack a digital audio input to my old car head unit
Reply #1 –
Sorry for the double post, I could not figure out how to edit my first post.
Figured it out. One of my wires fell off and I had soldered it to the wrong pin. Retracing my steps with the logic analyzer helped me diagnose.
No need to worry about pull up settings (I think)
Check it out. I can read the 24 bit (memory address?) using the 16 bit Selector register 0x1F 0xF7!
As I switch between radio and CD input, the third byte changes from 0x80 to 0x81! Nice!
(1)>4
Set speed:
1. ~5KHz
2. ~50KHz
3. ~100KHz
4. ~400KHz
(1)>4
Ready
I2C>(1)
Searching I2C address space. Found devices at:
0x22(0x11 W) 0x38(0x1C W) 0x39(0x1C R)
I2C>[0x38 0x1f 0xFE [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xFE ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x88 ACK 0x1F ACK 0x41
NACK
I2C STOP BIT
I2C>[0x38 0x1f 0xf7 [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xF7 ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x20 ACK 0x04 ACK 0x80
NACK
I2C STOP BIT
I2C>[0x38 0x1f 0xf7 [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xF7 ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x20 ACK 0x04 ACK 0x80
NACK
I2C STOP BIT
I2C>[0x38 0x1f 0xf7 [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xF7 ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x20 ACK 0x24 ACK 0x81
NACK
I2C STOP BIT
I2C>[0x38 0x1f 0xf7 [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xF7 ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x20 ACK 0x24 ACK 0x81
NACK
I2C STOP BIT
I2C>[0x38 0x1f 0xf7 [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xF7 ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x20 ACK 0x24 ACK 0x81
NACK
I2C STOP BIT
I2C>[0x38 0x1f 0xf7 [0x39 r:3 ]
I2C START BIT
WRITE: 0x38 ACK
WRITE: 0x1F ACK
WRITE: 0xF7 ACK
I2C START BIT
WRITE: 0x39 ACK
READ: 0x20 ACK 0x04 ACK 0x80
NACK
I2C STOP BIT
I2C>