Cybot - Communications

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Welcome to the CYBOT Communications Page

Power-up

Processor 1 only, no other boards added to the 6 way connector

Processor 1 attempts to write address device 0x57 6 times, each time receiving a no-acknowledge

When this has failed, processor 1 then attempts to read address device 0x7F

With no Sonar Processor, no acknowledgements are received

Processor 1 and Sonar processor

The same process is executed, address 0x57 is attempted, again each time receiving a no-acknowledge

When this has failed, processor 1 then attempts to read address device 0x7F.

The read request is now acknowledged, The Sonar processor UC2 responds to address 0x7F.

UC2 responds with 0011xxxx where xxxx is the switch setting, described below.

Depending upon the selected mode, approx 3 seconds after power-on, processor 1 will begin communications again.

The data rate of the communications can be clearly seen to deviate.
This is due to the master device generating the clock with respect to the other functions it must perform.

Typically it was seen that the clock was off for 4.2 x 5us and 2.5 x 5us on.
This gives an approximate clock frequency of 29.8Khz.

You can also see on the captured transfers that the master holds the clock low.
This is detailed in the I2C spec, to prevent unwanted interruptions during system processes.

This does not seem to be required in this system as it is a single master, or is assumed to be.
Maybe the future upgrade board will remove this bus hold state, allowing a multi-master system.

Connections

PIN	FUNCTION
1	0v
2	+6v
3	+5v
4	I2C CLOCK
5	I2C DATA
6	RESET

RESET is generated by the Sonar Processor PCB

Mode Information

The following table shows the switch setting, master request and system responses.

I will provide more information as I discover it.

A switch setting of 0 represents no connection.
The microcontroller actually reads this as a high signal due to the pull-up resistor on the UC2 board.

A switch setting of 1 represents the switch is ON or CLOSED, connecting the pin to 0v.

Therefore a switch setting of 0000 means that all the switches are open, all the inputs are pulled up.
The microcontroller will see 1111, this is reported as 0x3F to processor 1.

The information shows the data in the format of data, in hexadecimal, read or write bit and acknowledge bit.

Switch Setting 1 2 3 4	Mode	Response to 0x7F W A	Broadcast	Response	Comment
U U U U	Fast Light Follow	0x3F A	None	None
D U U U	Slow light follow	0x3E A	None	None
U D U U	Fast avoid objects	0x3D A	78 W A	00 A	approx every 48ms
D D U U	Slow avoid objects	0x3C A	78 W A	00 A	approx every 48ms
U U D U	??	0x3B A	0A W N	none	constant request
D U D U	Line Follow	0x3A A	None	none
U D D U	Follow objects	0x39 A	78 W A	00 A	approx every 48ms extra packet every approx 4 sec
D D D U	Line Follow	0x38 A	None	none
U U U D	??	0x37 A	0C W N	none	constant request
D U U D	??	0x36 A	0C W N	none	constant request
U D U D	??	0x35 A	0D W N	none	constant request
D D U D	??	0x34 A	0D W N	none	constant request
U U D D	??	0x33 A	0E W N	none	constant request
D U D D	??	0x32 A	0E W N	none	constant request
U D D D	??	0x31 A	0F W N	none	constant request
D D D D	??	0x30 A	0F W N	none	constant request

D = DOWN U = UP
modes 2,3 and 6 are sonar related.
The 00h response the data packet relative to sonar measurement.

Data communication captures:

Start-up communication
Start-up communication - zoom in
Start-up communication and sonar io response in light follow mode (0000)
Zoom in of the above, showing read and acknowledge detail
Start-up communication and sonar io response in line follow mode (0101)

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