Owner manual

67 Rev. F - 15 February, 2001
T89C51RD2
Figure 22. Set-Up Modes Configuration
8.9.4. Programming Algorithm
To program the T89C51RD2 the following sequence must be exercised:
• Check the signature bytes
• Check the HSB (VSB mode)
If the security bits are activated, the following commands must be done before programming:
• Unlock test modes (PEULCK mode, pulse 55h and AAh)
• Chip erase (CERR mode)
• Write FFh in the HSB (PGMS mode)
• Write the signature bytes content in the XAF
• As the boot loader and the XAF content is lost after a "chip erase", it must be reprogrammed if needed.
• Disable programming access (PELCK mode)
To write a page in the FLASH memory, execute the following steps:
• Step 0: Enable programming access (PEULCK mode)
• Step 1: Activate the combination of control signals (PGML mode)
• Step 2: Input the valid address on the address lines (High order bits of the address must be stable during the
complete ALE low time)
• Step 3: Activate the combination of control signals (PGML mode)
• Step 4: Input the appropriate data on the data lines.
• Step 5: Pulse ALE/PROG once.
Repeat step 2 through 5 changing the address and data for end of a 128 bytes page
• Step 6: Enable programming access (PEULCK mode)
• Step 7: Activate the combination of control signals (PGMC mode)
+5V
V
CC
P0.0-P0.7
P1.0-P1.7
P2.0-P2.5
VSS
GND
D0-D7
A0-A7
A8-A13
RST
EA
ALE/PROG
PSEN
P2.6
P2.7
P3.3
P3.7
P3.6
XTAL1
4 to 6 MHz
CONTROL
SIGNALS*
PROGRAM
SIGNALS*
P3.4
A14
P3.5
A15