C541U_99 Datasheet, PDF (182/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

OTP Memory Operation
C541U
10.7 Access of Version Bytes
The C541U provides three version bytes at address locations FCH, FDH, and FEH. The information
stored in the version bytes, is defined by the mask of each microcontroller step, Therefore, the
version bytes can be read but not written. The three version bytes hold information as manufacturer
code, device type, and stepping code.
For reading of the version bytes the control lines must be used according table 10-2 and figure 10-
7. The address of the version byte must be applied at the port 1 address lines. PALE must not be
activated.
PMSEL1,0
0,1
PALE
Port 2
FC
FD
FE
Port 0
Ver. 0 Ver. 1 Ver. 2
PROG
PRD
MCT03422
Figure 10-7
Read Version Byte(s) Waveform
Version bytes are typically used by programming systems for adapting the programming firmware
to specifc device characteristics such as OTP size etc.
Note: The 3 version bytes are implemented in a way that they can be also read during normal
program execution mode as a mapped register with bit RMAP in SFR SYSCON set. The
addresses of the version bytes in normal mode and programming mode are identical and
therefore they are located in the SFR address range.
The first step of the C541U will contain the following information at the version bytes :
Name
Version Byte 0
Version Byte 1
Version Byte 2
Address
FCH
FDH
FEH
Value
C5H
C1H
01H
Future steppings of the C541U will have a different version byte 2 (incremented value. version bytes
0 and 1 will remain unchanged for future steppings of the C541U.
Semiconductor Group
10-11
1997-10-01