mc68hc05bs8 Freescale Semiconductor, Inc, mc68hc05bs8 Datasheet - Page 122

• Manufacturer Part Number: mc68hc05bs8
• Description: Mc68hc05 Family Of Low-cost Single-chip Microcontrollers.
• Manufacturer: Freescale Semiconductor, Inc

A
A.4.1
ELAT - EPROM Latch Control
PGM - EPROM Program Command
A.4.2
Programming the EPROM of the MC68HC705BS8 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 $1900 is programmed with $00.
CLR
LDX
BSET
LDA
STA
BSET
JSR
CLR
A-4
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 1ms.
5) Clear the PGM and the ELAT bits.
Address
$001C
PCR
#$00
1,PCR
#$00
$1900,X
0,PCR
DELAY
PCR
Program 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 ELATA is 1. This bit should
not be set unless a programming voltage is applied to the V
EPROM address and data bus configured for normal reads.
Programming power connected to the EPROM array. If ELAT 1 then
PGM = 0.
Programming power disconnected from the 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
;program
;call delay subroutine for 1ms
;reset PCR
bit 5
RESERVED
MC68HC705BS8
bit 4
bit 3
bit 2
ELAT
bit 1
PP
pin while programming, but
PGM
bit 0
uuuu uu00
on reset
MC68HC05BS8
PP
State
pin.
TPG