Datasheet
Chapter 8 Analog-to-Digital Converter (ADC10V1)
MC9S08QD4 Series MCU Data Sheet, Rev. 6
Freescale Semiconductor 95
8.1.1.1 Channel Assignments
The ADC channel assignments for the MC9S08QD4 series devices are shown in Table 8-1. Reserved
channels convert to an unknown value.
8.1.1.2 Alternate Clock
The ADC is capable of performing conversions using the MCU bus clock, the bus clock divided by two,
or the local asynchronous clock (ADACK) within the module. The alternate clock, ALTCLK, input for the
MC9S08QD4 series MCU devices is not implemented.
8.1.1.3 Hardware Trigger
The ADC hardware trigger, ADHWT, is output from the real-time interrupt (RTI) counter. The RTI counter
can be clocked by either ICSERCLK or a nominal 32 kHz clock source within the RTI block.
The period of the RTI is determined by the input clock frequency and the RTIS bits. The RTI counter is a
free running counter that generates an overflow at the RTI rate determined by the RTIS bits. When the
ADC hardware trigger is enabled, a conversion is initiated upon a RTI counter overflow.
Table 8-1. ADC Channel Assignment
ADCH Channel Input Pin Control ADCH Channel Input Pin Control
00000 AD0 PTA0/ADC1P0 ADPC0 10000 AD16 V
SS
N/A
00001 AD1 PTA1/ADC1P1 ADPC1 10001 AD17 V
SS
N/A
00010 AD2 PTA2/ADC1P2 ADPC2 10010 AD18 V
SS
N/A
00011 AD3 PTA3/ADC1P3 ADPC3 10011 AD19 V
SS
N/A
00100 AD4 Vss N/A 10100 AD20 V
SS
N/A
00101 AD5 Vss N/A 10101 AD21 V
SS
N/A
00110 AD6 Vss N/A 10110 AD22 Reserved N/A
00111 AD7 Vss N/A 10111 AD23 Reserved N/A
01000 AD8 V
SS
N/A 11000 AD24 Reserved N/A
01001 AD9 V
SS
N/A 11001 AD25 Reserved N/A
01010 AD10 V
SS
N/A 11010 AD26 Temperature
Sensor
1
1
For information, see Section 8.1.1.5, “Temperature Sensor.”
N/A
01011 AD11 V
SS
N/A 11011 AD27 Internal Bandgap
2
2
Requires BGBE =1 in SPMSC1 see Section 5.8.8, “System Power Management Status and Control 1 Register (SPMSC1).”
For value of bandgap voltage reference see Appendix A.5, “DC Characteristics.”
N/A
01100 AD12 V
SS
N/A 11100 V
REFH
V
DD
N/A
01101 AD13 V
SS
N/A 11101 V
REFH
V
DD
N/A
01110 AD14 V
SS
N/A 11110 V
REFL
V
SS
N/A
01111 AD15 V
SS
N/A 11111 Module
Disabled
None N/A