added dtmf-bin translation table

ihu-mpu communicaton over rs232 not spi


git-svn-id: https://svn.spreadspace.org/mur.sat@173 7de4ea59-55d0-425e-a1af-a3118ea81d4c

2 files changed, 24 insertions, 7 deletions

diff --git a/doc/protocols/ground-crx.txt b/doc/protocols/ground-crx.txt
index 504d914..1a92ab0 100644
--- a/doc/protocols/ground-crx.txt
+++ b/doc/protocols/ground-crx.txt
@@ -18,7 +18,27 @@ Frame
 Checksum:
 ---------
 
-XOR over Signs intrepreted as HEX (0-9A-D#*) -> (0-9A-F)
+XOR over Signs intrepreted as 4-bit numbers (see translation table below)
+
+   DTMF-Sign  |  Number
+  ------------+----------
+       D      |    0
+       1      |    1
+       2      |    2
+       3      |    3
+       4      |    4
+       5      |    5
+       6      |    6
+       7      |    7
+       8      |    8
+       9      |    9
+       0      |   10
+       *      |   11
+       #      |   12
+       A      |   13
+       B      |   14
+       C      |   15
+ 
 
 Codes:
 ------
diff --git a/doc/protocols/ihu-mpu.txt b/doc/protocols/ihu-mpu.txt
index 9a25432..aa3c5f8 100644
--- a/doc/protocols/ihu-mpu.txt
+++ b/doc/protocols/ihu-mpu.txt
@@ -5,17 +5,14 @@ Protocol Definition between IHU and MPU
 Introduction
 ------------
 
-The two controllers use SPI to communicate with each other. In
-addition to the 4 Lines needed for SPI there are 3 extra connections
+The two controllers use RS-232 with TTL-Levels to communicate with each other.
+In addition to the 2 Lines needed for RS-232 there are 2 extra connections
 between IHU and MPU. One is for the IHU to control the power of the MPU.
 Holding this pin low prevents the MPU from running and therefore keeps
 power consumption at a minimum also the whole payload electronic connected
 to the MPU has to be in powerdown when this PIN goes low. The second line
 is for reset. After a high to low transition the MPU has to perform a 
 hardware reset. This also resets any payload hardware.
-The third line is used by the MPU to inform the IHU that it wishes
-to communicate. After this line goes high the IHU has to start the
-communication by starting the SPI clock.
 
 
 Frames
@@ -36,7 +33,7 @@ of the message. In a message N bytes long, where Byte 1 is the first and Byte
 N the last Byte, CS is calculated starting with Byte 1 (0xAA) and ending
 with Byte N-1 (last DATA Byte)
 The minimum frame length is 4 Bytes and the maximum is 260 Bytes.
-The bytes have to be sent LSB first. Multi byte fields have to be sent
+The bytes have to be sent LSB first. Multi-byte fields have to be sent
 in Little-Endian format.