CDC3205G-C Micronas, CDC3205G-C Datasheet - Page 158

• Manufacturer Part Number: CDC3205G-C
• Description: Automotive Controller Family The Device is a Microcontroller For Use in Automotive Applications.the On-chip Cpu is an Arm Processor ARM7TDMI with 32-bit Data And Address Bus, Which Supports Thumb format Instructions.
• Manufacturer: Micronas

CDC 32xxG-C
25.1. Principle of Operation
25.1.1. General
A UART module contains a receive shift register that serves
to receive a telegram via its RX input. A FIFO is affixed to it
that stores two previously received telegrams.
A transmit shift register serves to transmit a telegram via its
TX output.
Other features include a receive compare function, flexible
interrupt generation and handling, and a set of control, error
and status flags that facilitate management of the UART by
SW.
The interrupt source output of this module is routed to the
Interrupt Controller logic. But this does not necessarily select
it as input to the Interrupt Controller. Check section “Interrupt
Controller” for the actually selectable sources and how to
select them.
A programmable baud rate generator generates the required
bit clock frequency.
For the effect of CPU clock modes on the operation of this
module refer to section “CPU and Clock System” (see
Table 4–1 on page 37).
A UART module is only capable to receive telegrams that dif-
fer by no more than
25.1.2. Hardware settings
The polarity of most RX and TX connections of the UART is
settable by HW Options (See table 25–1 and figure 25–2).
Refer to “HW Options” for setting them.
Fig. 25–2:
25.1.3.2. Telegram Format
The format of a telegram is configured in the Control and
Status register UAxC. A telegram starts with a start bit fol-
lowed by the data field. The data field consists of 7 or 8 data
bit. There can be a parity bit after the data field. The telegram
is finished by one or two stop bits (see Table 25–3 on
page 160).
156
f
0
SR0.UARTx
Context Diagram
clk
UARTx
2.5% from its own baud rate setting.
rx
tx
HW Option
1
HW Option
0
1
0
1
1
UARTx-TX
UARTx-RX
SO
June 12, 2003; 6251-579-1PD
SI
25.1.3. Initialization
After reset, a UART is in standby mode (inactive).
Prior to entering active mode, proper SW configuration of the
U-Ports assigned to function as RX input and TX output has
to be made (Table 25–1). The RX port has to be configured
Special In and the TX port has to be configured Special Out.
Refer to “Ports” for details.
For entering active mode of a UART, set the respective
enable bit (Table 25–1).
Prior to operation, the desired baud rate, telegram format,
compare address and interrupt source configuration have to
be made.
25.1.3.1. Baud Rate Generator
The receive and transmit baud rate is internally generated.
The Baud Rate registers UAxBR0 (low byte) and UAxBR1
(high byte) serve to enter the desired 13bit setting. Write
UAxBR0 first, UAxBR1 last.
The baud rate generator is a 13bit down-counter which is
clocked by f
Its output frequency f
the baud rate (bit/second).
BR
=
Value of Baud Rate Registers
f
----------------------------------------------------------------------------------------------
sample
Value of Baud Rate Registers
0
. It generates the sample frequency:
=
--------------------------------------------------------------------------------
Value of Baud Rate Registers
sample
PRELIMINARY DATA SHEET
f
0
is divided by eight to generate
f
0
=
+
---------------- - 1
BR
1
f
0
8
8
+
–
=
1
f
-------------- -
Micronas
sample
8