diff options
| author | Christian Pointner <equinox@mur.at> | 2011-07-26 00:27:12 +0000 |
|---|---|---|
| committer | Christian Pointner <equinox@mur.at> | 2011-07-26 00:27:12 +0000 |
| commit | 6652b6812299a713aa2d0545eb7fcc86c7df7d93 (patch) | |
| tree | 0340d15ed9cb680f58895e8f26fcd786e35246a6 /doc/protocols/ihu-ttx.txt | |
| parent | ttx multiple byte rx code added (not tested yet) (diff) | |
renamed cpu to mpu at docs
some improvments and fixes at doc/protocols
git-svn-id: https://svn.spreadspace.org/mur.sat@61 7de4ea59-55d0-425e-a1af-a3118ea81d4c
Diffstat (limited to 'doc/protocols/ihu-ttx.txt')
| -rw-r--r-- | doc/protocols/ihu-ttx.txt | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/doc/protocols/ihu-ttx.txt b/doc/protocols/ihu-ttx.txt index e5ff572..9eb46e9 100644 --- a/doc/protocols/ihu-ttx.txt +++ b/doc/protocols/ihu-ttx.txt @@ -6,13 +6,15 @@ Bitstream --------- 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 a wakeup pulse -with a minimun length of 1µs. After this it has to wait at least 3ms for the TTX -to wake up and switch to a higher oscillator frequency. The data is transferred -MSB first in groups of 8bits (1 Octet). 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. +The IHU is the master and drives the clock. On idle SCL is at logic 0 and SDA +should be tristate to save power. When the IHU want's to communicate it has to +generate a wakeup pulse with a minimun length of 1µs. After this it has to wait +at least 3ms for the TTX to wake up and switch to a higher oscillator frequency. +The data is transferred MSB first in groups of 8bits (1 Octet). 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 _________________ _________________ @@ -29,9 +31,9 @@ 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 +LEN octets of data. When all the data has been transferred the master (IHU) switches SDA to input and clocks in on byte as acknowledge. The aknowledge is a one byte XOR -checksum over all octets (including the command/len octet). +checksum over all octets (including the CMD/LEN octet). Field-length: 1 LEN 1 +---------+----------------+--------+ @@ -45,7 +47,7 @@ Commands ~~~~~~~ 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) + that disables any further broadcasts. Hex '1' ~~~~~~~ @@ -78,6 +80,15 @@ Commands so that the next beacon will follow after the normal beacon period. This command has no data. + Hex 'D' + ~~~~~~~ + + This command sends the latest telemetry values to the TTX. This values will be used + in the very next beacon and until new values get transmitted. In case of a power fail + these values will be reset by the IHU so the TTY doesn't have to store this values in + non volatile memory. + The contents and length of the data field are to be defined. + Hex 'F' ~~~~~~~ |