Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 3.7.4 ADC Clock Register

I/O Registers
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 55
In 8-bit mode, this 8-bit result register holds the eight MSBs of the 10-bit result. This register is updated
each time an ADC conversion completes. In 8-bit mode, this register contains no interlocking with ADRH.
3.7.4 ADC Clock Register
This register selects the clock frequency for the ADC, selecting between modes of operation.
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.
Address: $0042
Bit 7654321Bit 0
Read: AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
Write:RRRRRRRR
Reset: Unaffected by reset
R= Reserved
Figure 3-8. ADC Data Register Low (ADRL) Right Justified Mode
Address: $0042
Bit 7654321Bit 0
Read: AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2
Write:RRRRRRRR
Reset: Unaffected by reset
R= Reserved
Figure 3-9. ADC Data Register Low (ADRL) 8-Bit Mode
Address: $0043
Bit 7654321Bit 0
Read:
ADIV2 ADIV1 ADIV0 ADICLK MODE1 MODE0 0
0
Write: R
Reset:00000100
R= Reserved
Figure 3-10. ADC Clock Register (ADCLK)
Table 3-2. ADC Clock Divide Ratio
ADIV2 ADIV1 ADIV0 ADC Clock Rate
0 0 0 ADC input clock ÷ 1
0 0 1 ADC input clock ÷ 2
0 1 0 ADC input clock ÷ 4
0 1 1 ADC input clock ÷ 8
1 X X ADC input clock ÷ 16
X = don’t care