MC68HC705BD3 FREESCALE [Freescale Semiconductor, Inc], MC68HC705BD3 Datasheet - Page 103

• Manufacturer Part Number: MC68HC705BD3
• Description: High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

14.3.1
The EPROM Programming Control register controls the actual programming of the EPROM in the
MC68HC705BD3.
ELAT - EPROM Latch Control
PGM - EPROM Program Command
14.3.2
Programming the EPROM of the MC68HC705BD3 is as follows:
The last action may be carried out in a single CPU write operation. It is important to remember
that an external programming voltage must be applied to the V
should be equal to V
Example shows address $2000 is programmed with $00.
CLR
LDX
BSET
LDA
STA
MC68HC05BD3
1 (set)
0 (clear) –
1 (set)
0 (clear) –
1) Set the ELAT bit.
2) Write the data to be programmed to the address to be programmed.
3) Set the PGM bit.
4) Delay for the appropriate amount of time.
5) Clear the PGM and the ELAT bits.
Address
$001D
PCR
#$00
1,PCR
#$00
$2000,X
Programming Control Register (PCR)
EPROM Programming Sequence
–
–
bit 7
DD
EPROM address and data bus configured for programming (writes to
EPROM cause address data to be latched). EPROM is in
programming mode and cannot be read if ELAT is 1. This bit is not
able be set when no V
EPROM address and data bus configured for normal reads.
Programming power switched on to EPROM array. If ELAT 1 then
PGM=0.
Programming power switched off to EPROM array.
during normal operation.
bit 6
;reset PCR
;load index register with 00
;set ELAT bit
;load data=00 in to A
;latch data and address
bit 5
MC68HC705BD3
bit 4
PP
voltage is applied to the V
bit 3
bit 2
ELAT
bit 1
PP
pin while programming, but
PGM
bit 0
PP
pin.
on reset
---- --00
State
TPG
14-3
14