C167CS datasheet(316/517 Pages) INFINEON

316 / 517 page

C167CS

Derivatives

The Bootstrap Loader

User’s Manual

15-6

V2.0, 2000-07

15.4

Choosing the Baudrate for the BSL

The calculation of the serial baudrate for ASC0 from the length of the first zero byte that

is received, allows the operation of the bootstrap loader of the C167CS with a wide range

of baudrates. However, the upper and lower limits have to be kept, in order to ensure

proper data transfer.

The C167CS uses timer T6 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 C167CS the maximum deviation between

the internal initialized baudrate for ASC0 and the real baudrate of the host should be

below 2.5%. The deviation (FB, in percent) between host baudrate and C167CS

baudrate can be calculated via the formula below:

Note: Function (FB) does not consider the tolerances of oscillators and other devices

supporting the serial communication.

This baudrate deviation is a nonlinear function depending on the CPU clock and the

baudrate of the host. The maxima of the function (FB) increase with the host baudrate

due to the smaller baudrate prescaler factors and the implied higher quantization error

(see Figure 15-3).

fCPU

S0BRL

()

⋅

----------------------------------------------

BC167CS =

S0BRL

–

--------------------

---

CPU

Host

--------------

⋅

Contr

Host

–

Contr

-------------------------------------

100%

⋅

2,5%

≤

C167CS Datasheet(PDF) 316 Page - Infineon Technologies AG

C167CS Datasheet(HTML) 316 Page - Infineon Technologies AG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL