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4.4 Programming the Flash Modules
4.4.1 External Flash
A separate programming voltage of 12V is required for programming the external
Flash-EEPROM. This can be controlled and should not be connected permanently for
safety reasons.
• Manual control
The programming voltage Vpp12 can be activated with the DIP switch "Vpp12 on"
(SW100-1). It is then permanently connected to the external flash. To protect the
flash memory from being overwritten by accident, the switch should be "off" when
no programming is to take place.
• Automatic control
If the "Vpp12 auto" option is enabled (SW100-2 on), the Vpp12 programming volt-
age can be switched on by the MPC555 program or by the connected ETAS
emulator test probe (ETK).
— Control by CPU program
Vpp12 is activated by entering "1" in the programming voltage control register
(cf. Figure 5-2). Vpp12 is deactivated by entering a "0" in the register.
— Control by the emulator test probe (ETK)
The ETK can activate the programming voltage by applying a high level at the
SGEPEE signal (CO508, pin 137). This makes it possible for the ETK to pro-
gram the external flash.
4.4.2 Internal Flash of the MPC555
Two prerequisites must be fulfilled for programming the internal flash memory of the
MPC555:
1. Vpp5 (5 V) programming voltage is connected.
2. Programming is enabled by the high level at the EPEE pin.
The Vpp5 programming voltage can be applied separately by closing the "Vpp5 on"
(SW100-3) DIP switch. To protect the internal flash from being overwritten by accident,
the switch should be "off" when no programming is to take place.
Enabling programming via the EPEE pin
1. The pin can be permanently connected to a high level
with the "EPEE" (SW100-4 on) switch
2. The ETK can enable the programming mode by a high level
at the SGEPEE signal (C0508, pin 137).
EVB555
Quick Reference
MOTOROLA
4-17
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