C509-L_97 Datasheet, PDF (267/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Bootstrap Loader
C509-L
10.5 Description of the Bootstrap Loader Subroutines
This section describes the software of the bootstrap loader with its most important subroutines and
start addresses, which can be used by the customer for own purposes. This technical reference is
valid for C509-L parts with a stepping code “CA” or later.
Table 10-5 shows the subroutines of the bootstrap loader which can be used by the customer, when
executing custom programs.
Table 10-5
Bootstrap Loader Subroutines - Survey
Address Function
000EH SendByte
0016H SendAckn
001BH SendBlockErr
0074H CalcBaudRate
00A6H CheckBaud
Registers
Description
In : A - Byte to send
Out : None
Send a byte to the serial interface 0
In : None
Out : None
Send an acknowledge code (55H) to
the serial interface 0
In : None
Out : None
Send a block error code (FFH) to the
serial interface 0
In : TH0/TL0 - measured
value for test byte in
T0
Out : R1/R2 -
value for S0REL
In : None
Out : None
Calculate the value for the 10 bit baud
rate generator reload register S0REL
of the serial interface 0 depending on
the value of T0 (TH0/TL0) for receiving
the test byte (00H)
The complete baud rate
synchronization:
1. Prepare the timer 0 for
measurement
2. Wait for the test byte from host
3. Measure the time between the start
bit and the stop bit
4. Calculate the baudrate from the
value of timer 0 (T0)
5. Initialize the serial interface 0 by
setting the baud rate and the serial
parameters (8N2)
6. Send an acknowledge code (55H) to
the host
Semiconductor Group
10-29
1997-10-01