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8XC196MC, MD, MH USER’S MANUAL
C-6
AD_COMMAND
AD_COMMAND
Address:
Reset State:
1FACH
80H
The A/D command (AD_COMMAND) register selects the A/D channel number to be converted,
controls whether the A/D converter starts immediately or with an EPA command, and selects the
conversion mode.
7 0
— M1 M0 GO ACH3 ACH2 ACH1 ACH0
Bit
Number
Bit
Mnemonic
Function
7 — Reserved; for compatibility with future devices, write zeros to these bits.
6:5 M1:0 A/D Mode†
These bits determine the A/D mode.
M1 M0 Mode
0 0 10-bit conversion
0 1 8-bit conversion
1 0 threshold detect high
1 1 threshold detect low
4 GO A/D Conversion Trigger††
Writing this bit arms the A/D converter. The value that you write to it
determines at what point a conversion is to start.
0 = EPA initiates conversion
1 = start immediately
3:0 ACH3:0 A/D Channel Selection
Write the A/D conversion channel number to these bits.
†
While a threshold-detection mode is selected for an analog input pin, no other conversion can be
started. If another value is loaded into AD_COMMAND, the threshold-detection mode is disabled
and the new command is executed.
††
It is the act of writing to the GO bit, rather than its value, that starts a conversion. Even if the GO bit
has the desired value, you must set it again to start a conversion immediately or clear it again to
arm it for an EPA-initiated conversion.