MCR908JL3EMPE Freescale Semiconductor, MCR908JL3EMPE Datasheet - Page 80

• Manufacturer Part Number: MCR908JL3EMPE
• Description: IC MCU 4K FLASH 8MHZ 28-DIP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MCR908JL3EMPE

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Peripherals: LED, LVD, POR, PWM
• Number Of I /o: 23
• Program Memory Size: 4KB (4K x 8)
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 12x8b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Connectivity: -

Monitor ROM (MON)
Upon power-on reset, if the received bytes of the security code do not match the data at locations
$FFF6–$FFFD, the host fails to bypass the security feature. The MCU remains in monitor mode, but
reading a Flash location returns an invalid value and trying to execute code from Flash causes an illegal
address reset. After receiving the eight security bytes from the host, the MCU transmits a break character,
signifying that it is ready to receive a command.
To determine whether the security code entered is correct, check to see if bit 6 of RAM address $80 is
set. If it is, then the correct security code has been entered and Flash can be accessed.
If the security sequence fails, the device should be reset by a power-on reset and brought up in monitor
mode to attempt another entry. After failing the security sequence, the Flash module can also be mass
erased by executing an erase routine that was downloaded into internal RAM. The mass erase operation
clears the security code locations so that all eight security bytes become $FF (blank).
80
PTB0
V
RST
NOTES:
The MCU does not transmit a break character until after the host sends the
eight security bytes.
DD
1 = Echo delay, 2 bit times
2 = Data return delay, 2 bit times
4 = Wait 1 bit time before sending next byte.
FROM HOST
FROM MCU
Figure 7-7. Monitor Mode Entry Timing
4096 + 32 OSCXCLK CYCLES
MC68HC908JL3E Family Data Sheet, Rev. 4
24 BUS CYCLES
1
NOTE
4
1
1
2
4
Freescale Semiconductor
1