MC68HC705JP7 Datasheet, PDF (185/242 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
EPROM/OTPROM
EPROM Registers
ELAT — EPROM Bus Latch Bit
This read/write bit configures address and data buses for
programming the EPROM array. EPROM data cannot be read when
ELAT is set. Clearing the ELAT bit also clears the EPGM bit. Reset
clears ELAT.
1 = Address and data buses configured for EPROM programming
of the array. The address and data buses are latched in the
EPROM array when a subsequent write to the array is made.
Data in the EPROM array cannot be read.
0 = Address and data buses configured for normal operation
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
register as follows:
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, t_EPGM.
4. Clear the ELAT and EPGM bits in the EPROG register.
13.3.2 Mask Option Register
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 MΩ or open)
4. STOP instruction (enable or disable)
5. Low-voltage reset (enable or disable)
MC68HC705JJ7 • MC68HC705JP7 — REV 4
MOTOROLA
EPROM/OTPROM
For More Information On This Product,
Go to: www.freescale.com
Advance Information
185