MC68HC908AS32A Datasheet, PDF (65/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

I/O Registers
3.7.2 ADC Data Register
One 8-bit result register is provided. This register is updated each time an ADC conversion completes.
Address: $0039
Bit 7
6
5
4
3
2
1
Bit 0
Read: AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
Reset:
= Unimplemented
Indeterminate after reset
Figure 3-4. ADC Data Register (ADR)
3.7.3 ADC Input Clock Register
This register selects the clock frequency for the ADC.
Address: $003A
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
ADIV2 ADIV1 ADIV0 ADICLK
Write:
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 3-5. ADC Input Clock Register (ADICLK)
ADIV2–ADIV0 — ADC Clock Prescaler Bits
ADIV2, ADIV1, and ADIV0 form a 3-bit field which selects the divide ratio used by the ADC to generate
the internal ADC clock. Table 3-2 shows the available clock configurations. The ADC clock should be
set to approximately 1 MHz.
Table 3-2. ADC Clock Divide Ratio
ADIV2 ADIV1
0
0
0
0
0
1
0
1
1
X
X = don’t care
ADIV0
0
1
0
1
X
ADC Clock Rate
ADC input clock ÷ 1
ADC input clock ÷ 2
ADC input clock ÷ 4
ADC input clock ÷ 8
ADC input clock ÷ 16
MC68HC908AS32A Data Sheet, Rev. 2.0
Freescale Semiconductor
65