Servo 1.0 protocol

From BitWizard WIKI
Revision as of 12:19, 12 January 2013 by Rew (talk | contribs) (write ports)

Jump to: navigation, search


The protocol for the SERVO boards will be explained on this page.

This page describes both the SPI and the I2C version. See SPI versus I2C protocols for the explanation about how the protocols work in general.

The default address of the servo board is 0x86.

write ports

The ports on the servo board just set a single byte-value. So writing more than one byte to such a port is redundant.

The spi_servo board defines several ports.

port function
0x20 Set servo 0 position
0x21 Set servo 1 position
0x22 Set servo 2 position
0x23 Set servo 3 position
0x24 Set servo 4 position
0x25 Set servo 5 position
0x26 Set servo 6 position
0xf0 change address.

read ports

The spi_servo board supports two read ports:

port function
0x01 identification string. (terminated with 0).
0x20 read servo 0 position
0x21 read servo 1 position
0x22 read servo 2 position
0x23 read servo 3 position
0x24 read servo 4 position
0x25 read servo 5 position
0x26 read servo 6 position


For SPI in the examples below, "data sent" means the data on the MOSI line, while "data received" means the data on the MISO line. when MISO reads "xx" you should ignore the data. When MOSI reads "xx" it doesn't matter what you send.

For I2C in the examples below, you should first initiate a "write" transaction with the data in the "data sent column". Don't send the "xx" bytes. Then you initiate a "read" transaction, and you will get the data in the "data received" column (and again not the "xx" bytes).

read identification

read the identification string of the board. ('spi_servo 1.0').

data sent data recieved explanation
0x87 xx select destination with address 0x82 for READ.
0x01 xx identify
xx 0x73 's'
xx 0x70 'p'
xx 0x69 'i'
xx ... etc.