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MC68HC11PH8 Datasheet, PDF (182/264 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit | |||
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9.3.2 Multiple-channel operation
There are two types of multiple-channel operation. In the ï¬rst type (SCAN = 0), a selected group
of four channels is converted once only. The ï¬rst result is stored in A/D result register 1 (ADR1),
and the fourth result is stored in ADR4. After the fourth conversion is complete, all conversion
activity is halted until a new conversion command is written to the ADCTL register. In the second
type of multiple-channel operation (SCAN = 1), conversions continue to be performed on the
selected group of channels with the ï¬fth conversion being stored in register ADR1 (replacing the
earlier conversion result for the ï¬rst channel in the group), the sixth conversion overwriting ADR2,
and so on.
9.4
Control, status and results registers
9.4.1 ADCTL â A/D control and status register
A/D control & status (ADCTL)
Address bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
State
on reset
$0030 CCF 0 SCAN MULT CD CC CB CA u0uu uuuu
All bits in this register can be read or written, except bit 7, which is a read-only status indicator,
and bit 6, which always reads as zero. Write to ADCTL to initiate a conversion. To quit a conversion
in progress, write to this register and a new conversion sequence begins immediately.
9
CCF â Conversions complete ï¬ag
1 (set) â All four A/D result registers contain valid conversion data.
0 (clear) â At least one of the A/D result registers contains invalid data.
A read-only status indicator, this bit is set when all four A/D result registers contain valid
conversion results. Each time the ADCTL register is overwritten, this bit is automatically cleared
to zero and a conversion sequence is started. In the continuous mode, CCF is set at the end of
the ï¬rst conversion sequence.
Bit 6 â Not implemented; always reads zero.
SCAN â Continuous scan control
1 (set) â A/D conversions take place continuously.
0 (clear) â Each of the four conversions is performed only once.
When this control bit is clear, the four requested conversions are performed once to ï¬ll the four
result registers. When this control bit is set, the four conversions are repeated continuously with
the result registers updated as data becomes available.
MOTOROLA
9-8
ANALOG-TO-DIGITAL CONVERTER
TPG
MC68HC11PH8
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