Programming Algorithm
Verify 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)
• Step 8: Input the valid address on the address lines.
• Step 9: Pulse ALE/PROG once the specified write time is reached.
Repeat step 0 through 9 changing the address and data until the entire array or until the
end of the object file is reached (See Figure 32.)
• Step 10: Disable programming access (PELCK mode)
Verify must be done after each byte or block of bytes is programmed. In either case, a
complete verify of the programmed array will ensure reliable programming of the
T89C51RD2.
P 2.7 is used to enable data output.
To verify the T89C51RD2 code the following sequence must be exercised:
• Step 1:Activate the combination of program and control signals (PGMV)
• Step 2: Input the valid address on the address lines.
• Step 3: Read data on the data lines.
Repeat step 2 through 3 changing the address for the entire array verification
(See Figure 32.).
78 T89C51RD2
4243G–8051–05/03