Kein Basic, aber so geht der ASlgorirthmus
[c]
unsigned char sbus_read(unsigned char ack,unsigned char reverse)
// reads a byte form the Sensibus and gives an acknowledge in case of
"ack=1"
{
unsigned char i, val;
val=0;
datadir(0); // DATA als Eingang zum Lesen
i=(reverse?0x01:0x80); // shift bit for masking
while(i)
{
clk1(); // clk for SENSI-BUS
if(datain()) val|=i; // read bit
clk0();
if(reverse) i<<=1; else i>>=1;
}
datadir(1); // DATA als Ausgang
data(!ack); // in case of "ack==1" pull down
DATA-Line
clk1(); // clk #9 for ack
clk0();
datadir(0); // DATA als Eingang zum Lesen
return val;
}
unsigned char lut[] =
{
0, 49, 98, 83, 196, 245, 166, 151, 185, 136, 219,
234, 125, 76, 31, 46, 67, 114, 33, 16, 135,
182, 229, 212, 250, 203, 152, 169, 62, 15,
92, 109, 134, 183, 228, 213, 66, 115, 32,
17, 63, 14, 93,108, 251, 202, 153, 168,
197, 244, 167, 150, 1, 48, 99, 82, 124, 77,
30, 47, 184, 137, 218, 235, 61, 12, 95,
110, 249, 200, 155, 170, 132, 181, 230,
215, 64, 113, 34, 19, 126, 79, 28, 45, 186,
139, 216, 233, 199, 246, 165, 148, 3, 50,
97, 80, 187, 138, 217, 232, 127, 78, 29,
44, 2, 51, 96, 81, 198, 247, 164, 149, 248,
201, 154, 171, 60, 13, 94, 111, 65, 112,
35, 18, 133, 180, 231, 214, 122, 75, 24,
41, 190, 143, 220, 237, 195, 242, 161, 144,
7, 54, 101, 84, 57, 8, 91, 106, 253, 204,
159, 174, 128, 177, 226, 211, 68, 117, 38,
23, 252, 205, 158, 175, 56, 9, 90, 107, 69,
116, 39, 22, 129, 176, 227, 210, 191, 142,
221, 236, 123, 74, 25, 40, 6, 55, 100, 85,
194, 243, 160, 145, 71, 118, 37, 20, 131,
178, 225, 208, 254, 207, 156, 173, 58, 11,
88, 105, 4, 53, 102, 87, 192, 241, 162,
147, 189, 140, 223, 238, 121, 72, 27, 42,
193, 240, 163, 146, 5, 52, 103, 86, 120,
73, 26, 43, 188, 141, 222, 239, 130, 179,
224, 209, 70, 119, 36, 21, 59, 10, 89, 104,
255, 206, 157, 172
};
int sbus_measure(unsigned char command)
{
int i,msb,lsb;
unsigned char crc;
if(sbus_send(command)) return -1;
for ( i=0; i<655; i++ ) if ( !datain() ) break; // wait until sensor
has finished the measurement
if (datain()) return -1; // or timeout is reached
msb = sbus_read(ACK,0); // read the first byte (MSB)
lsb = sbus_read(ACK,0); // read the second byte (LSB)
crc = sbus_read(noACK,1); // read checksum
// 4 status register bits go into sent crc, but they are 0 if sensor
is as we want it
if(crc!=lut[lut[lut[command]^msb]^lsb]) return -1; // crc check fails
return (msb<<8)|lsb;
}
[/c)
Wichtig ist die 1 bei sbus_read, das kombiniert die Bits in anderer
Reihenfolge (Bits rückwätrs) als bei den Messwerten.
