CyBENCH :: Robotics - Electronics Resources
Home Projects Cybot ScrapBots Part Salvage Site Map Links
  CYBOT PAGES
Comm's Index
Sonar Comm's
  SITE INFO
Contact Info
Disclaimer

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

PINFUNCTION
10v
2+6v
3+5v
4I2C CLOCK
5I2C DATA
6RESET

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
ModeResponse to 0x7F W ABroadcastResponseComment
U U U U
Fast Light Follow0x3F ANoneNone 
D U U U
Slow light follow0x3E ANoneNone 
U D U U
Fast avoid objects0x3D A78 W A00 Aapprox every 48ms
D D U U
Slow avoid objects0x3C A78 W A00 Aapprox every 48ms
U U D U
??0x3B A0A W Nnoneconstant request
D U D U
Line Follow0x3A ANonenone 
U D D U
Follow objects0x39 A78 W A00 A approx every 48ms extra packet every approx 4 sec
D D D U
Line Follow0x38 ANonenone 
U U U D
??0x37 A0C W Nnoneconstant request
D U U D
??0x36 A0C W Nnoneconstant request
U D U D
??0x35 A0D W Nnoneconstant request
D D U D
??0x34 A0D W Nnoneconstant request
U U D D
??0x33 A0E W Nnoneconstant request
D U D D
??0x32 A0E W Nnoneconstant request
U D D D
??0x31 A0F W Nnoneconstant request
D D D D
??0x30 A0F W Nnoneconstant 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)

Return to TOP of the page