MC68HC705B16CFN Freescale Semiconductor, MC68HC705B16CFN Datasheet - Page 76
Manufacturer Part Number
IC MCU 2.1MHZ 15K OTP 52-PLCC
Specifications of MC68HC705B16CFN
Number Of I /o
Program Memory Size
15KB (15K x 8)
Program Memory Type
256 x 8
352 x 8
Voltage - Supply (vcc/vdd)
4.5 V ~ 5.5 V
-40°C ~ 85°C
Package / Case
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
When SCDR is read, it contains the last data byte received, provided that the receiver is enabled.
The receive data register full flag bit (RDRF) in the SCSR is set to indicate that a data byte has
been transferred from the input serial shift register to the SCDR; this will cause an interrupt if the
receiver interrupt is enabled. The data transfer from the input serial shift register to the SCDR is
synchronized by the receiver bit rate clock. The OR (overrun), NF (noise), or FE (framing) error
flags in the SCSR may be set if data reception errors occurred.
An idle line interrupt is generated if the idle line interrupt is enabled and the IDLE bit (which detects
idle line transmission) in SCSR is set. This allows a receiver that is not in the wake-up mode to
detect the end of a message or the preamble of a new message, or to resynchronize with the
transmitter. A valid character must be received before the idle line condition or the IDLE bit will not
be set and idle line interrupt will not be generated.
The SCP0 and SCP1 bits function as a prescaler for SCR0–SCR2 to generate the receiver baud rate
and for SCT0–SCT2 to generate the transmitter baud rate. Together, these eight bits provide multiple
transmitter/receiver rate combinations for a given crystal frequency (see
should only be written to while both the transmitter and receiver are disabled (TE=0, RE=0).
SCT0 – SCT2
There is a fixed rate divide-by-16 before the transmitter to compensate for the inherent divide-by-16 of the receiver (sampling).
This means that by loading the same value for both the transmitter and receiver baud rate selector, the same baud rates can
SERIAL COMMUNICATIONS INTERFACE
Figure 6-2 SCI rate generator division
SCP0 – SCP1
Baud rate register
Internal processor clock
SCR0 – SCR2
6-2). This register