Freescale Semiconductor, Inc.
GENERAL RELEASE SPECIFICATION
6.2.2 Bootloader Mode
Bootloader mode is entered upon the rising edge of RESET if the IRQ pin is twice
8
2
the V voltage and the TCAP/PD7 pin is at logic one. In bootloader mode, the
DD
user EEPROM and mask option register (MOR) bytes can be erased and
programmed. Figure 6-1 shows the bootloader circuit. PTC4 determines whether
erasing or programming will occur as shown in Table 6-2.
3
4
Table 6-2. Bootloader Functions
PTC4
Function
Bulk Erase/Blank Verify
Bulk Erase/Program/Verify
5
0
1
6
7
Bulk Erase/Blank Verify
To use the bootloader circuit to bulk erase the user EEPROM, follow this
sequence:
8
9
1. Close RESET switch and PTC4 switch so these pins are held low.
2. Apply 12 V power to IRQ.
10
11
12
13
14
A
3. Release RESET.
4. Programming LED will turn on while bulk erase is occurring.
5. When bulk erase is finished, programming LED will turn off.
6. When blank verify is finished, verify LED will turn on.
7. Close RESET switch.
8. Remove 12 V from IRQ, then remove power.
16
17
18
19
20
OPERATING MODES
MC68HC805P18
6-2
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