MC68HC08JK1 Datasheet, PDF (100/198 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Monitor ROM (MON)
9.4.2 Baud Rate
The communication baud rate is dependant on oscillator frequency and
the state of PTB3 upon monitor mode entry. When PTB3 is high, the
divide by ratio is 1024. If the PTB3 pin is at logic zero upon entry into
monitor mode, the divide by ratio is 512.
Table 9-3. Monitor Baud Rate Selection
Oscillator Input Frequency
4.9152 MHz
9.8304 MHz
4.9152 MHz
PTB3
0
1
1
Baud Rate
9600 bps
9600 bps
4800 bps
9.4.3 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. (See Figure 9-2 and Figure 9-3.)
NEXT
START
START
BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 ^STOP BIT
BIT
Figure 9-2. Monitor Data Format
NEXT
START
START
$A5 BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 STOP BIT
BIT
BREAK
START
BIT BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
STOP
BIT 7 BIT ^NEXT
START
BIT
Figure 9-3. Sample Monitor Waveforms
The data transmit and receive rate can be anywhere from 4800 baud to
28.8k-baud. Transmit and receive baud rates must be identical.
9.4.4 Echoing
Technical Data
100
As shown in Figure 9-4, the monitor ROM immediately echoes each
received byte back to the PTB0 pin for error checking.
Monitor ROM (MON)
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MC68H(R)C08JL3 — Rev. 4
MOTOROLA