SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 264

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

15.4
Calculation of the serial baudrate for ASC0 from the length of the first zero byte received
allows the bootstrap loader of the C164CM to operate with a wide range of baudrates.
However, the upper and lower limits must be maintained in order to ensure proper data
transfer.
The C164CM uses timer T3 to measure the length of the initial zero byte. The
quantization uncertainty of this measurement implies the first deviation from the real
baudrate. The next deviation is implied by the computation of the S0BRL reload value
from the timer contents. The formula below shows the association:
For a correct data transfer from the host to the C164CM the maximum deviation between
the internal initialized baudrate for ASC0 and the real baudrate of the host should be
below 2.5%. The deviation (F
baudrate can be calculated via the formula below:
Note: Function (F
This baudrate deviation is a nonlinear function depending on the CPU clock and the
baudrate of the host. The maxima of the function (F
due to the smaller baudrate prescaler factors and the implied higher quantization error
(see
User’s Manual
B
S0BRL
F
B
C164CM
=
Figure
supporting the serial communication.
B
------------------------------------ -
Contr
=
=
B
Choosing the Baudrate for the BSL
T3 18
------------------- -
Contr
15-3).
----------------------------------------------- -
32
–
36
–
B
Host
B
S0BRL
) does not consider the tolerances of oscillators and other devices
f
CPU
,
100%
+
1
T3
B
, in percent) between host baudrate and C164CM
=
,
9
-- -
8
F
B
------------- -
B
f
CPU
Host
15-6
2,5%
B
) increase with the host baudrate
C164CM/C164SM
Bootstrap Loader
Derivatives
V1.0, 2002-02