Cookies and Capacitors

Reading ADB bytes

Fri, Apr 27, 2012 at 4:54AM

It works. Here is a screenshot I just took of an Apple Desktop Bus Mouse II’s register 0. Arrows are drawn to show what words make up the bytes. To attain this, I opened a serial monitor, and sent the byte B0011 11 00. Bits 0-1 is the register location: I told it register 0. Bits 2-3 is the command: a binary 3 means TALK. Finally, bits 4-7 are the device address. Mice (and other ‘relative’ devices) are, by default, at location 3.

The bytes sent were: 1101110 11111010. However, we should not think of this as two separate bytes, but rather 16 individual bits. Their meanings have been matched to their value in the screenshot linked above.