68HC705SP7 datasheet(181/230 Pages) FREESCALE

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EPROM/OTPROM

EPROM Registers

MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0

General Release Specification

EPROM/OTPROM

Whenever the ELAT bit is cleared, the EPGM bit is also cleared. Both

the EPGM and the ELAT bit cannot be set using the same write

instruction. Any attempt to set both the ELAT and EPGM bit on the same

write instruction cycle will result in the ELAT bit being set and the EPGM

bit being cleared. To program a byte of EPROM, manipulate the EPROG

1. Set the ELAT bit in the EPROG register.

2. Write the desired data to the desired EPROM address.

3. Set the EPGM bit in the EPROG register for the specified

programming time, tEPGM.

4. Clear the ELAT and EPGM bits in the EPROG register.

13.3.2 Mask Option Register (MOR)

The mask option register (MOR) shown in Figure 13-2 is an EPROM

byte that controls eight mask options. The MOR is unaffected by reset.

The erased state of the MOR is $00. The options that can be

programmed by the MOR are:

1. Port software programmable pulldown devices (enable or disable)

2. Startup delay after stop (16 or 4064 cycles)

3. Oscillator shunt resistor (2 M or open)

4. STOP instruction (enable or disable)

5. Low-voltage reset (enable or disable)

6. Port A external interrupt function (enable or disable)

7. IRQ trigger sensitivity (edge-triggered only or both edge- and

level-triggered)

8. COP watchdog (enable or disable)

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