In this section, some pins of this device
are referenced by signal names describing their functionality during parallel
programming, please refer to the following figure and table Pin Name Mapping in
this section. Pins not described in the following table are referenced by pin names.
The XA1/XA0 pins determine the action
executed when the XTAL1 pin is given a positive pulse. The bit coding is shown in the
table XA1 and XA0 Coding in this section.
When pulsing WR
or OE, the command loaded determines the action executed. The
different Commands are shown in the table Command Byte Bit Coding in this
section.
Figure 1. Parallel Programming
Table 1. Pin Name Mapping
Signal
Name in Programming Mode |
Pin
Name |
I/O |
Function |
RDY/BSY |
PD1 |
O |
0:
Device is busy programming, 1: Device is ready for new command |
OE |
PD2 |
I |
Output
Enable (Active low) |
WR |
PD3 |
I |
Write
Pulse (Active low) |
BS1 |
PD4 |
I |
Byte
Select 1 (“0” selects Low byte, “1” selects High byte) |
XA0 |
PD5 |
I |
XTAL
Action Bit 0 |
XA1 |
PD6 |
I |
XTAL
Action Bit 1 |
PAGEL |
PD7 |
I |
Program
memory and EEPROM Data Page Load |
BS2 |
PC2 |
I |
Byte
Select 2 (“0” selects Low byte, “1” selects 2’nd High byte) |
DATA |
{PC[1:0]: PB[5:0]} |
I/O |
Bi-directional Data bus (Output when OE is
low) |
Table 2. Pin Values Used to Enter
Programming Mode
Pin |
Symbol |
Value |
PAGEL |
Prog_enable[3] |
0 |
XA1 |
Prog_enable[2] |
0 |
XA0 |
Prog_enable[1] |
0 |
BS1 |
Prog_enable[0] |
0 |
Table 3. XA1 and XA0 Coding
XA1 |
XA0 |
Action
when XTAL1 is Pulsed |
0 |
0 |
Load
Flash or EEPROM Address (High or low address byte determined by
BS1) |
0 |
1 |
Load
Data (High or Low data byte for Flash determined by BS1) |
1 |
0 |
Load
Command |
1 |
1 |
No
Action, Idle |
Table 4. Command Byte Bit Coding
Command
Byte |
Command
Executed |
1000
0000 |
Chip
Erase |
0100
0000 |
Write
Fuse bits |
0010
0000 |
Write
Lock bits |
0001
0000 |
Write
Flash |
0001
0001 |
Write
EEPROM |
0000
1000 |
Read
Signature Bytes and Calibration byte |
0000
0100 |
Read
Fuse and Lock bits |
0000
0010 |
Read
Flash |
0000
0011 |
Read
EEPROM |