MC9RS08KA8RM Datasheet, PDF (94/190 Pages) Freescale Semiconductor, Inc – MC9RS08KA8 Features

Chapter 10 10-bit Analog-to-Digital Converter (RS08ADC10V1)
10.1.1 Module Configurations
This section provides device-specific information for configuring the ADC on MC9RS08KA8 series
devices.
10.1.1.1 Analog Supply and Voltage Reference Connections
The V_DDAD and V_REFH sources for the ADC are internally connected to the V_DD pin. The V_SSAD and
V_REFL sources for the ADC are internally connected to the V_SS pin.
10.1.1.2 Alternate Clock
The ADC can perform 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
MC9RS08KA8 series MCU devices is not implemented.
10.1.1.3 Hardware Trigger
The ADC hardware trigger ADHWT is output from the real-time interrupt (RTI) counter. ICSERCLK or
a nominal 1 kHz clock source within the RTI block can clock the RTI counter.
The input clock frequency and the RTIS bits determine the RTI period. 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 initiates upon an RTI counter overflow.
The RTI can be configured to cause a hardware trigger in MCU run, wait, and stop.
NOTE
To get quick RTI hardware trigger, the RTI clock source must be a high
frequency external clock source.
10.1.1.4 Analog Pin Enables
The ADC on MC9RS08KA8 series devices contains only two analog pin enable registers, APCTL1 and
APCTL2.
The ADC channel assignments for the MC9RS08KA8 series devices are shown in the table below.
Reserved channels convert to an unknown value. Channels which are connected to an I/O pin have an
associated pin control bit as shown.
ADCH
00000
00001
00010
00011
00100
00101
Channel
AD0
AD1
AD2
AD3
AD4
AD5
Table 10-1. ADC Channel Assignment
Input
PTA0//ADP0
PTA1/ADP1
PTA2/ADP2
PTA3/ADP3
PTB0/ADP4
PTB1/ADP5
Pin Control
ADPC0
ADPC1
ADPC2
ADPC3
ADPC4
ADPC5
ADCH Channel
Input
Pin Control
MC9RS08KA8 Series Reference Manual, Rev. 3
94
Freescale Semiconductor