MC908QL4 FREESCALE [Freescale Semiconductor, Inc], MC908QL4 Datasheet - Page 195

• Manufacturer Part Number: MC908QL4
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Table 16-1
may be entered after a power-on reset (POR) and will allow communication at 9600 baud provided one
of the following sets of conditions is met:
IRQ = V
The rising edge of the internal RST signal latches the monitor mode. Once monitor mode is latched, the
values on PTA1 and PTA4 pins can be changed.
Once out of reset, the MCU waits for the host to send eight security bytes (see
security bytes, the MCU sends a break signal (10 consecutive 0s) to the host, indicating that it is ready to
receive a command.
Freescale Semiconductor
•
•
•
2
3
5
1 μF
1 μF
DB9
If $FFFE and $FFFF do not contain $FF (programmed state):
–
–
If $FFFE and $FFFF contain $FF (erased state):
–
–
If $FFFE and $FFFF contain $FF (erased state):
SS
The external clock is 9.8304 MHz
IRQ = V
The external clock is 9.8304 MHz
IRQ = V
+
+
(internal oscillator is selected, no external clock required)
shows the pin conditions for entering monitor mode. As specified in the table, monitor mode
1
3
4
5
7
8
C1+
C1–
C2+
C2–
Figure 16-12. Monitor Mode Circuit (Internal Clock, No High Voltage)
TST
DD
MAX232
(this can be implemented through the internal IRQ pullup)
V+
V–
16
15
2
10
6
1 μF
9
V
DD
+
+
MC68HC908QL4 Data Sheet, Rev. 7
1 μF
2
74HC125
1
+
3
1 μF
74HC125
6
4
10 kΩ
5
V
DD
10 kΩ
*
N.C.
N.C.
RST (PTA3)
OSC1 (PTA5)
IRQ (PTA2)
PTA0
16.3.2
Monitor Module (MON)
Security). After the
PTA1
PTA4
V
V
DD
SS
* Value not critical
V
N.C.
N.C.
DD
0.1 μF
195