XC68HC705F32 Motorola, XC68HC705F32 Datasheet - Page 96

• Manufacturer Part Number: XC68HC705F32
• Description: MICROCONTROLLER
• Manufacturer: Motorola

9
When the internal RC oscillator is being used as the conversion clock, the following limitations
apply.
ADON — A/D converter on
The ADON bit allows the user to enable/disable the A/D converter.
When the A/D converter is switched on, it takes a time t
(see
Power-on or external reset will clear the ADON bit, thus disabling the A/D converter.
CH3 – CH0 — A/D channel selection
The CH3–CH0 bits allow the user to determine which channel of the A/D converter multiplexer is
selected (see
MOTOROLA
9-4
Table
1) Due to the frequency tolerance of the RC oscillator and its asynchronism
2) The conversion process runs at the nominal 1.5MHz rate but the conversion
3) If the system clock is running faster than the RC oscillator, the RC oscillator
1 (set)
0 (clear) –
with regard to the MCU bus clock, the conversion complete flag (COCO)
must be used to determine when a conversion sequence has been
completed.
results must be transferred to the MCU result registers synchronously with
the MCU bus clock in order that conversion time is limited to a maximum of
one channel per bus clock cycle.
should be switched off and the system clock used as the conversion clock.
16-5). During this time A/D conversion results may be inaccurate.
Table
–
9-2).
A/D converter is switched on.
A/D converter is switched off.
CH3
0
0
0
0
0
0
0
0
1
1
1
1
Table 9-2 A/D channel assignment
CH2
0
0
0
0
1
1
1
1
1
1
1
1
CH1
A/D CONVERTER
0
0
1
1
0
0
1
1
0
0
1
1
CH0
0
1
0
1
0
1
0
1
0
1
0
1
Channel
10
11
0
1
2
3
4
5
6
7
8
9
ADON
(V
REFH
for the current sources to stabilize
Factory test
AD0/PD0
AD1/PD1
AD2/PD2
AD3/PD3
AD4/PD4
AD5/PD5
AD6/PD6
AD7/PD7
Signal
V
V
REFH
REFL
+V
REFL
)/2
MC68HC05F32
TPG