diff options
| -rw-r--r-- | doc/protocols/ihu-ttx.txt | 84 |
1 files changed, 81 insertions, 3 deletions
diff --git a/doc/protocols/ihu-ttx.txt b/doc/protocols/ihu-ttx.txt index e447066..2fc518c 100644 --- a/doc/protocols/ihu-ttx.txt +++ b/doc/protocols/ihu-ttx.txt @@ -2,7 +2,85 @@ Protocol Definition between IHU and TTX ======================================= -Introduction ------------- +Bitstream +--------- -to be defined... +IHU and TTX communicate using a simple serial synchronous bus (SDA,SCL). +The IHU is the master and drives the clock. On Idle the SCL and SDA are both +at logic 0. When the IHU want's to communicate it has to generate wakeup pulse +with a minimun length of 1µs. After this it has to wait at least 3ms for the TTX +wake up and switch to a higher oscillator frequency. The data is transferred in +octets MSB first. SDA must be stable before the clock goes high. A Clock pulse +must be at least 4µs long and the data has to stay valid for at least 17µs. After +each octet there must be a break of 50µs. + + | wake up | 1st octet | break | 2nd octet + _________________ _________________ +SDA | | | | +-----------//-+ +---------//--+ +----//------------ + _ ____ ____ ____ ____ +SCL | | | | | | | | | | +-----+ +---//--+ +------------+ +---//---+ +----------------//--+ +---- + + | 3ms | 4µs| 13µs | | 50µs | + + +Frames +------ + +Every frame starts with 4 bit command code and a 4 bit length field. After this follow +len octets of data. When all the data has been transferred the Master (IHU) switches +SDA as input and clocks in on byte as acknowledge. The aknowledge is a one byte XOR +checksum over all octets (including the command/len octet). + +Field-length: 1 LEN 1 + +---------+----------------+--------+ +Name | CMD/LEN | DATA | CS | + +---------+----------------+--------+ + +Commands +-------- + + Hex '0' + ~~~~~~~ + + This tells the TTX to shut up. The TTX will send out one aknowledge over cw and after + that disables any further broadcasts. (Safe mode) + + Hex '1' + ~~~~~~~ + + This is the reverse of the '0' command. The TTX will send out an aknowledge over cw + and reenables broadcasting of beacons. + + Hex '2' + ~~~~~~~ + + The command sets a new beacon interval. The data is one octet containing the new beacon + interval in seconds. + + Hex '3' + ~~~~~~~ + + This sets a new cw speed. It is followed by three octets representing the dot, dash + and word space times. + + Hex 'A' + ~~~~~~~ + + This instructs the TTX to send out a aknowledge frame over cw. The command + has 1 octet of data containing the ASCII Code of the aknowledge to send out. + + Hex 'B' + ~~~~~~~ + + This inscructs the TTX to send out a beacon immediately. It also resets the timer + so that the next beacon will follow after the normal beacon period. This command has + no data + + Hex 'F' + ~~~~~~~ + + This transmits a new format string for the standard beacon. The data is a variable + length string containing ASCII characters each standing for a beacon element to send + out. |