Rabbit RabbitCore User Manual page 47

unsigned int anaInDriver(unsigned int cmd,
unsigned int len);
Reads the voltage of an analog input channel by serial-clocking an 8-bit command to the ADS7870 A/D
converter by the Direct Mode method. This function assumes that Mode1 (most significant byte first) and
the A/D converter oscillator have been enabled. See anaInConfig() for the setup.
The conversion begins immediately after the last data bit has been transferred. An exception error will
occur if Direct Mode bit D7 is not set.
PARAMETERS
cmd contains a gain code and a channel code as follows.
D7—1; D6–D4—Gain Code; D3–D0—Channel Code
Use the following calculation and the tables below to determine cmd:
cmd = 0x80 | (gain_code*16) + channel_code
Channel Code
0
1
2
†
3
4
5
6
7*
* Negative input is ground.
† Not accessible on RCM3700 Prototyping Board
len, the output bit length, is always 12 for 11-bit conversions
RETURN VALUE
User's Manual
Gain Code
0
1
2
3
4
5
6
7
Differential Input
Channel Code
Lines
+AIN0 -AIN1
+AIN2 -AIN3
+AIN4 -AIN5
+AIN6 -AIN7
-AIN0 +AIN1
-AIN2 +AIN3
-AIN4 +AIN5
-AIN6 +AIN7
Multiplier
x1
x2
x4
x5
x8
x10
x16
x20
Single-Ended
Input Lines
8 AIN0
9 AIN1
10 AIN2
11 AIN3
12 AIN4
13 AIN5
14 AIN6
15 AIN7
4–20 mA
*
Lines
AIN0*
AIN1*
AIN2*
AIN3
AIN4
AIN5
AIN6
AIN7*
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