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h1. Work with UART (ASM)

Observe transmit and receive messages via UART more details(on Assembler).

In code examples constant list is used, which need required with directive " .include "

<pre>

.include "HDL50001_pcf.inc"

</pre>

h2. а) Transmit via UART

h3. 1. Allow alternative port functions. 

Now, produce two development kits, in which using UART0(HW1-MCp04) and UART3(LDM-MCp04).

Observe assembler commands for allowance alternative port functions.

For UART0:

<pre>

getl 0x00000F00

wrl @1, GPIOB_BPS

</pre>

For UART3:

<pre>

getl 0x00000F00

wrl @1, GPIOD_BPS

</pre>

h3. 2. Configurate UART on transmission, set baudrate.

For setting UART on transmission write value in control register:

For UART0:

<pre>

getl 0x00000002

wrl @1, UART0_CR

</pre>

For UART3:

<pre>

getl 0x00000002

wrl @1, UART3_CR

</pre>

For setting baudrate use division factor BRDIV = Fsys/(8*Fuart - 1)

For speed 38400 kbit/s:

For UART0:

<pre>

 getl 0x00000104

 wrl @1, UART0_BDR

</pre>

For UART3:

<pre>

 getl 0x00000104

 wrl @1, UART3_BDR

</pre>

h3. 3. Check transmitter FIFO on full.

For UART0:

<pre>

fifo_tx_full:

    rdl UART0_ST

    getl 0x00000200

    and @1, @2

    je @1, fifo_tx_full

    jne @2, send_byte

complete

</pre>

For UART3:

<pre>

fifo_tx_full:

    rdl UART3_ST

    getl 0x00000200

    and @1, @2

    je @1, fifo_tx_full

    jne @2, send_byte

complete

</pre>

h3. 4. Transmit byte via UART.

For UART0:

<pre>

    getb 0xAB 

    wrb @1, UART0_DATA

</pre>

For UART3:

<pre>

    getb 0xAB 

    wrb @1, UART3_DATA

</pre>

As a result you can get simple example - transmission byte via UART with baudrate 38400 kbit/s:

For UART0:

<pre>

.include "HDL50001_pcf.inc"

.text

preset_UART0:

    getl 0x00000F00

    wrl @1, GPIOB_BPS

    getl 0x00000104

    wrl @1, UART0_BDR

    getl 0x00000002

    wrl @1, UART0_CR

    jmp fifo_tx_full

complete

fifo_tx_full:

    rdl UART0_ST

    getl 0x00000200

    and @1, @2

    je @1, fifo_tx_full

    jne @2, paragraph

complete

send_byte:

    getb 0xAB 

    wrb @1, UART0_DATA

complete

</pre>

For UART3 example is analogie. All UART examples are available in Repository, any questions about interfaces you can discuss at Community.

h2. б) Receive via UART

For reception byte via UART:

h3. 1. Allow alternative port functions (as 1 in "transmit" section)

h3. 2. Configurate UART on reception, set baudrate.

For setting UART on reception write value in control register:

For UART0:

<pre>

getl 0x00000001

wrl @1, UART0_CR

</pre>

For UART3:

<pre>

getl 0x00000001

wrl @1, UART3_CR

</pre>

Setting baudrate as 2 in "transmit" section.

h3. 3. Check receiver FIFO for new data

For UART0:

<pre>

fifo_rx_newb:

    rdl UART0_ST

    getl 0x00000001

    and @1, @2

    je @1, fifo_rx_newb

    jne @2, get_byte

complete

</pre>

For UART3:

<pre>

fifo_rx_newb:

    rdl UART3_ST

    getl 0x00000001

    and @1, @2

    je @1, fifo_rx_newb

    jne @2, get_byte

complete

</pre>

h3. 4. Receive byte

For UART0:

<pre>

rdb UART0_DATA

</pre>

For UART3:

<pre>

rdb UART3_DATA

</pre>