mc9s08qg4 Freescale Semiconductor, Inc, mc9s08qg4 Datasheet - Page 136

• Manufacturer Part Number: mc9s08qg4
• Description: Hcs08 Microcontrollers Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

Chapter 9 Analog-to-Digital Converter (S08ADC10V1)
9.5.1.2
In this example, the ADC module will be set up with interrupts enabled to perform a single 10-bit
conversion at low power with a long sample time on input channel 1, where the internal ADCK clock will
be derived from the bus clock divided by 1.
ADCCFG = 0x98 (%10011000)
ADCSC2 = 0x00 (%00000000)
ADCSC1 = 0x41 (%01000001)
ADCRH/L = 0xxx
data cannot be overwritten with data from the next conversion.
ADCCVH/L = 0xxx
APCTL1=0x02
APCTL2=0x00
136
Bit 7
Bit 6:5 ADIV
Bit 4
Bit 3:2 MODE
Bit 1:0 ADICLK
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3:2
Bit 1:0
Bit 7
Bit 6
Bit 5
Bit 4:0 ADCH
Holds results of conversion. Read high byte (ADCRH) before low byte (ADCRL) so that conversion
Holds compare value when compare function enabled
AD1 pin I/O control disabled. All other AD pins remain general purpose I/O pins
All other AD pins remain general purpose I/O pins
2. Update status and control register 2 (ADCSC2) to select the conversion trigger (hardware or
3. Update status and control register 1 (ADCSC1) to select whether conversions will be continuous
software) and compare function options, if enabled.
or completed only once, and to enable or disable conversion complete interrupts. The input channel
on which conversions will be performed is also selected here.
ADLPC
ADLSMP
ADACT
ADTRG
ACFE
ACFGT
COCO
AIEN
ADCO
Pseudo — Code Example
1
00
1
10
00
0
0
0
0
00
00
0
1
0
00001 Input channel 1 selected as ADC input channel
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 4
Configures for low power (lowers maximum clock speed)
Sets the ADCK to the input clock ÷ 1
Configures for long sample time
Sets mode at 10-bit conversions
Selects bus clock as input clock source
Flag indicates if a conversion is in progress
Software trigger selected
Compare function disabled
Not used in this example
Unimplemented or reserved, always reads zero
Reserved for Freescale’s internal use; always write zero
Read-only flag which is set when a conversion completes
Conversion complete interrupt enabled
One conversion only (continuous conversions disabled)
Freescale Semiconductor