MC908AP32CFBE Freescale, MC908AP32CFBE Datasheet - Page 183

• Manufacturer Part Number: MC908AP32CFBE
• Manufacturer: Freescale

Specifications of MC908AP32CFBE

• Cpu Family: HC08
• Device Core Size: 8b
• Frequency (max): 8MHz
• Interface Type: SCI/SPI
• Total Internal Ram Size: 2KB
• # I/os (max): 32
• Number Of Timers - General Purpose: 4
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: PQFP
• Program Memory Type: Flash
• Program Memory Size: 32KB
• Lead Free Status / RoHS Status: Compliant

12.3 IRSCI Module Overview
The IRSCI consists of a serial communications interface (SCI) and a infrared interface sub-module as
shown in
The SCI module provides serial data transmission and reception, with a programmable baud rate clock
based on the bus clock or the CGMXCLK.
The infrared sub-module receives two clock sources from the SCI module: SCI_R16XCLK and
SCI_R32XCLK. Both reference clocks are used to generate the narrow pulses during data transmission.
The SCI_R16XCLK and SCI_R32XCLK are internal clocks with frequencies that are 16 and 32 times the
baud rate respectively. Both SCI_R16XCLK and SCI_R32XCLK clocks are used for transmitting data.
The SCI_R16XCLK clock is used only for receiving data.
12.4 Infrared Functional Description
Figure 12-3
The infrared sub-module provides the capability of transmitting narrow pulses to an infrared LED and
receiving narrow pulses and transforming them to serial bits, which are sent to the SCI module. The
infrared sub-module receives two clocks from the SCI. One of these two clocks is selected as the base
clock to generate the 3/16, 1/16, or 1/32 bit width narrow pulses during transmission.
The sub-module consists of two main blocks: the transmit encoder and the receive decoder. When
transmitting data, the SCI data stream is encoded by the infrared sub-module. For every "0" bit, a narrow
"low" pulse is transmitted; no pulse is transmitted for "1" bits. When receiving data, the infrared pulses
should be detected using an infrared photo diode for conversion to CMOS voltage levels before
connecting to the RxD pin for the infrared decoder. The SCI data stream is reconstructed by stretching
the "0" pulses.
Freescale Semiconductor
Figure
shows the structure of the infrared sub-module.
For proper SCI function (transmit or receive), the bus clock MUST be
programmed to at least 32 times that of the selected baud rate.
When the infrared sub-module is disabled, signals on the TxD and RxD
pins pass through unchanged to the SCI module.
BUS CLOCK
CGMXCLK
12-2.
INTERFACE MODULE
COMMUNICATIONS
MC68HC908AP Family Data Sheet, Rev. 4
Figure 12-2. IRSCI Block Diagram
SERIAL
(SCI)
INTERNAL BUS
NOTE
SCI_R32XCLK
SCI_R16XCLK
SCI_RxD
SCI_TxD
SUB-MODULE
INFRARED
IRSCI Module Overview
SCTxD
SCRxD
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