Datasheet
Table Of Contents
- List of Sections
- Table of Contents
- List of Figures
- List of Tables
- Section 1. General Description
- 1.1 Contents
- 1.2 Introduction
- 1.3 Features
- 1.4 MCU Block Diagram
- 1.5 Pin Assignments
- 1.6 Pin Functions
- 1.6.1 Power Supply Pins (Vdd and Vss)
- 1.6.2 Oscillator Pins (OSC1 and OSC2)
- 1.6.3 External Reset Pin (RST)
- 1.6.4 External Interrupt Pin (IRQ)
- 1.6.5 Analog Power Supply Pin (VDDA)
- 1.6.6 Analog Ground Pin (VSSA)
- 1.6.7 Analog Ground Pin (AVSS/VREFL)
- 1.6.8 ADC Voltage Reference Pin (VREFH)
- 1.6.9 Analog Supply Pin (VDDAREF)
- 1.6.10 External Filter Capacitor Pin (CGMXFC)
- 1.6.11 Port A Input/Output (I/O) Pins (PTA7-PTA0)
- 1.6.12 Port B I/O Pins (PTB7/ATD7-PTB0/ATD0)
- 1.6.13 Port C I/O Pins (PTC5-PTC0)
- 1.6.14 Port D I/O Pins (PTD7-PTD0)
- 1.6.15 Port E I/O Pins (PTE7/SPSCK-PTE0/TxD)
- 1.6.16 Port F I/O Pins (PTF7-PTF0/TACH2)
- 1.6.17 Port G I/O Pins (PTG2/KBD2-PTG0/KBD0)
- 1.6.18 Port H I/O Pins (PTH1/KBD4-PTH0/KBD3)
- 1.7 I/O Pin Summary
- 1.8 Signal Name Conventions
- 1.9 Clock Source Summary
- Section 2. Memory Map
- Section 3. Random-Access Memory (RAM)
- Section 4. FLASH Memory
- Section 5. EEPROM
- Section 6. Configuration Register (CONFIG)
- Section 7. Central Processor Unit (CPU)
- Section 8. System Integration Module (SIM)
- Section 9. Clock Generator Module (CGM)
- 9.1 Contents
- 9.2 Introduction
- 9.3 Features
- 9.4 Functional Description
- 9.5 I/O Signals
- 9.5.1 Crystal Amplifier Input Pin (OSC1)
- 9.5.2 Crystal Amplifier Output Pin (OSC2)
- 9.5.3 External Filter Capacitor Pin (CGMXFC)
- 9.5.4 PLL Analog Power Pin (VDDA)
- 9.5.5 Oscillator Enable Signal (SIMOSCEN)
- 9.5.6 Crystal Output Frequency Signal (CGMXCLK)
- 9.5.7 CGM Base Clock Output (CGMOUT)
- 9.5.8 CGM CPU Interrupt (CGMINT)
- 9.6 CGM Registers
- 9.7 Interrupts
- 9.8 Low-Power Modes
- 9.9 CGM During Break Interrupts
- 9.10 Acquisition/Lock Time Specifications
- Section 10. Monitor ROM (MON)
- Section 11. Timer Interface Module A (TIMA)
- Section 12. Timer Interface Module B (TIMB)
- Section 13. Programmable Interrupt Timer (PIT)
- Section 14. Analog-to-Digital Converter (ADC)
- Section 15. Serial Communications Interface Module (SCI)
- Section 16. Serial Peripheral Interface Module (SPI)
- 16.1 Contents
- 16.2 Introduction
- 16.3 Features
- 16.4 Pin Name Conventions and I/O Register Addresses
- 16.5 Functional Description
- 16.6 Transmission Formats
- 16.7 Queuing Transmission Data
- 16.8 Error Conditions
- 16.9 Interrupts
- 16.10 Resetting the SPI
- 16.11 Low-Power Modes
- 16.12 SPI During Break Interrupts
- 16.13 I/O Signals
- 16.14 I/O Registers
- Section 17. Input/Output (I/O) Ports
- Section 18. External Interrupt (IRQ)
- Section 19. Keyboard Interrupt Module (KBI)
- Section 20. Computer Operating Properly (COP)
- Section 21. Low-Voltage Inhibit (LVI)
- Section 22. Break Module (BRK)
- Section 23. Electrical Specifications
- 23.1 Contents
- 23.2 Introduction
- 23.3 Absolute Maximum Ratings
- 23.4 Functional Operating Range
- 23.5 Thermal Characteristics
- 23.6 5.0-V DC Electrical Characteristics
- 23.7 EEPROM and Memory Characteristics
- 23.8 5.0-V Control Timing
- 23.9 Timer Interface Module Characteristics
- 23.10 ADC Characteristics
- 23.11 SPI Characteristics
- 23.12 Clock Generation Module Characteristics
- 23.13 FLASH Memory Characteristics
- Section 24. Mechanical Specifications
- Section 25. Ordering Information
Analog-to-Digital Converter (ADC)
Technical Data MC68HC908AB32 — Rev. 1.1
236 Analog-to-Digital Converter (ADC) Freescale Semiconductor
ADCH[4:0] — ADC Channel Select Bits
ADCH[4:0] form a 5-bit field which is used to select one of the eight
ADC channels, ATD7–ATD0. The channels are detailed in
Table 14-1. Care should be taken when using a port pin as both an
analog and digital input simultaneously to prevent switching noise
from corrupting the analog signal.
The ADC subsystem is turned off when the channel select bits are all
set to 1. This feature allows for reduced power consumption for the
MCU when the ADC is not being used.
NOTE: Recovery from the disabled state requires one conversion cycle to
stabilize.
The voltage levels supplied from internal reference nodes, as specified
in Table 14-1, are used to verify the operation of the ADC converter both
in production test and for user applications.
Table 14-1. Mux Channel Select
ADCH4 ADCH3 ADCH2 ADCH1 ADCH0 Input Select
00000 PTB0/ATD0
00001 PTB1/ATD1
00010 PTB2/ATD2
00011 PTB3/ATD3
00100 PTB4/ATD4
00101 PTB5/ATD5
00110 PTB6/ATD6
00111 PTB7/ATD7
01000
Reserved↓↓↓↓↓
11100
11101
V
REFH
11110
V
REFL
11111ADC power off
NOTE: If any unused channels are selected, the resulting ADC conversion will be unknown
or reserved.
