C509-L_97 SIEMENS [Siemens Semiconductor Group], C509-L_97 Datasheet - Page 267

• Manufacturer Part Number: C509-L_97
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

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
000E H
0016 H
001B H
0074 H
00A6 H
Semiconductor Group
SendByte
SendAckn
SendBlockErr
CalcBaudRate
CheckBaud
Registers
In : A - Byte to send
Out : None
In : None
Out : None
In : None
Out : None
In : TH0/TL0 - measured
Out : R1/R2 -
In : None
Out : None
value for test byte in
T0
value for S0REL
10-29
Description
Send a byte to the serial interface 0
Send an acknowledge code (55 H ) to
the serial interface 0
Send a block error code (FF H ) to the
serial interface 0
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 (00 H )
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 (55 H ) to
the host
Bootstrap Loader
1997-10-01
C509-L