Freescale Semiconductor 56F800 User Manual page 232

Register Definitions
Table 9-7. ADC Input Conversion for Sample Bits (Continued)
6
1
1
1
1
1
1
1
1
For example, to configure a sample as differential pair of AN4+, AN3-, SAMPLE[6:0] would be
1
LEGEND:
AN +, ANe+ : any of the ADC PLUS CHANNEL (even only) -AN0,AN2,AN4,AN6,AN8
even
AN -, ANo- : any of the ADC MINUS CHANNEL (odd only) -AN1,AN3,AN5,AN7,AN9
odd
When channels are configured as single-ended inputs (SAMPLEn[6] = 0), there are no
restrictions on assigning an analog channel (AN[0:9]) to a sample. Any sample slot, configured
for single-ended input, may contain any channel assignment.
However, when channels are configured as differential inputs (SAMPLEn[6] = 1), there is one
restriction. The plus terminal of the Analog Core can be one of the even channels (AN0, AN2,
AN4, AN6, AN8) only and the minus terminal of the Analog Core can be one of the odd channels
(AN1, AN3, AN5, AN7, AN9) only. This restriction is taken care with the channel select
(SAMPLEn[6:0]) code. When SAMPLEn[6] = 1, SAMPLEn[5:3] decode the plus channel and
SAMPLEn[2:0] decode the minus channel as shown in
for differential inputs, may contain any channel pair, but with the above restriction.
Codes not mentioned in
occur to the ADC if these restrictions are violated, however, measurement results are
unpredictable.
A mix and match combination of single-ended and differential configurations may exist in a
sequence of samples. For example:
• SAMPLE0: AN0+ and AN3- differential
• SAMPLE1: AN4 single-ended
• SAMPLE2: AN9 single-ended
• SAMPLE3: AN8+ and AN1- differential
• SAMPLE4: AN2 single-ended
• SAMPLE5: AN4+ and AN5- differential
• SAMPLE6: AN1 single-ended
20
SAMPLEn[6:0]
5 4 3 2 1
0 1 1 x
1 0 0 x
x x x 0 0
x x x 0 0
x x x 0 1
x x x 0 1
x x x 1 0
Others Others
0 1 0 0 0
Table 9-7 are reserved and should not be programmed. No damage will
56F826/827 User Manual, Rev. 3
Single Ended
0
x x –
x x –
0 –
1 –
0 –
1 –
0 –
–
1 -
Table 9-7. Any sample slot, configured
Differential
AN6+, AN0-
AN8+, AN0-
ANe+, AN1-
ANe+, AN3-
ANe+, AN5-
ANe+, AN7-
ANe+, AN9-
Reserved
AN4+, AN3-
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