Difference between revisions of "ARM Embedded Tutorial - Raspberry Pi Pico saying Hello via UART"

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Next peripheral on the list is the UART.
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{{ARM Embedded Tutorial - Raspberry Pi Pico saying Hello via UART}}
  
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You will now start to find a pattern, we add some objectfiles, implement a few dependencies that were defined as inline in the C-Code and in the end we have our app that outputs test via UART0 to the Pins 0+1 of the Pico:
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== Introduction ==
  
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    program Blinky;
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UART Interfaces are often used for debugging output, the pico is no exception to this rule.
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    {$L gpio.c.obj}
 
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    {$L uart.c.obj}
 
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    {$L clocks.c.obj}
 
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    {$L xosc.c.obj}
 
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    {$L pll.c.obj}
 
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    {$L watchdog.c.obj}
 
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    {$L platform.c.obj}
 
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    {$LinkLib gcc,static}
 
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    procedure clocks_init; external;
 
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    procedure gpio_init(gpio : longWord); external;
 
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    procedure gpio_set_function(gpio:longWord;fn:longWord); external;
 
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    function uart_init(var uart : TUART_Registers; baudrate:longWord) : longWord; external;
 
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    function uart_is_writable(var uart : TUART_Registers):boolean;
 
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    begin
 
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      result := (uart.fr and (1 shl 5)) = 0;
 
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    end;
 
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    procedure uart_puts(var uart : TUART_Registers; const s : string);
 
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    var
 
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      i : longWord;
 
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    begin
 
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      for i := 1 to length(s) do
 
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      begin
 
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        repeat
 
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        until uart_is_writable(uart);
 
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        uart.dr := longWord(s[i]);
 
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      end;
 
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    end;
 
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    procedure runtime_init;
 
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    const
 
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      RESETS_SAFE_BITS=    %1111111111100110110111111;
 
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      RESETS_PRECLOCK_BITS= %0001111000100110110111110;
 
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      RESETS_POSTCLOCK_BITS=%1110000111000000000000001;
 
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    begin
 
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      resets.reset_set := RESETS_SAFE_BITS;
 
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      resets.reset_clr := RESETS_PRECLOCK_BITS;
 
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      repeat
 
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      until (resets.reset_done and RESETS_PRECLOCK_BITS) = RESETS_PRECLOCK_BITS;
 
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      clocks_init;
 
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      resets.reset_clr := RESETS_POSTCLOCK_BITS;
 
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      repeat
 
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      until (resets.reset_done and RESETS_POSTCLOCK_BITS) = RESETS_POSTCLOCK_BITS;
 
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    end;
 
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    const
 
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      BAUD_RATE=115200;
 
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      UART_TX_PIN=0;
 
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      UART_RX_PIN=1;
 
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      GPIO_FUNC_UART=2;
 
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    var
 
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      i : longWord;
 
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    begin
 
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      runtime_init;
 
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      uart_init(uart0, BAUD_RATE);
 
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      gpio_set_function(UART_TX_PIN, GPIO_FUNC_UART);
 
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      gpio_set_function(UART_RX_PIN, GPIO_FUNC_UART);
 
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      repeat
 
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        uart_puts(uart0, 'Hello, UART!'+#13+#10);
 
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        for i := 0 to 300000 do ;
 
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      until 1=0;
 
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    end.
 
  
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one notable change is that you may have seen that we do not provide __aeabi_uidiv anymore, instead we link to libgcc.a and get (hopefully) best possible performnce for the div....
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This application is best tested with picoprobe, when you connect it to your development board as described in the Getting Started Guide chapter then the GPIO pins 0 and 1 are connected to the debug probe which makes them visible as a serial interface on your computer.
  
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This application is best tested with picoprobe, when you connect it to your development board as described in the Getting Started Guide chapter then the gpio pins 0 and 1 are connected to the debug probe which makes them visible as a serial interface on your computer.
+
Here's again our debugging setup on a breadboard, the picoprobe is on the right, the pico that will run our code is on the left:
  
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Connect your terminal program to the UART port and enjoy the message from your pico...
+
[[File:picoPicoDebug_Steckplatine.png|800px]]
 +
 
 +
<syntaxhighlight lang=pascal>
 +
program uart;
 +
{$MODE OBJFPC}
 +
{$H+}
 +
{$MEMORY 10000,10000}
 +
 
 +
uses
 +
  pico_uart_c,
 +
  pico_gpio_c,
 +
  pico_timer_c;
 +
const
 +
  BAUD_RATE=115200;
 +
begin
 +
  gpio_init(TPicoPin.LED);
 +
  gpio_set_dir(TPicoPin.LED,TGPIODirection.GPIO_OUT);
 +
  uart_init(uart0, BAUD_RATE);
 +
  gpio_set_function(TPicoPin.GP0_UART0_TX, TGPIOFunction.GPIO_FUNC_UART);
 +
  gpio_set_function(TPicoPin.GP1_UART0_RX, TGPIOFunction.GPIO_FUNC_UART);
 +
  repeat
 +
    gpio_put(TPicoPin.LED,true);
 +
    uart_puts(uart0, 'Hello, UART!'+#13+#10);
 +
    busy_wait_us_32(500000);
 +
    gpio_put(TPicoPin.LED,false);
 +
    busy_wait_us_32(500000);
 +
  until 1=0;
 +
end.
 +
</syntaxhighlight>
 +
 
 +
 
 +
 
 +
Connect your terminal program to the UART port and enjoy the message from your Pico.
 +
In this example we are using ansistrings, so the $MEMORY setting is important as we will use dynamically allocated AnsiStrings.
 +
To visually get confirmation that the app is running we additionally blink the LED on each turn of the main loop.
 +
 
 +
== See also ==
 +
 
 +
* [[ARM Embedded Tutorial - FPC and the Raspberry Pi Pico|ARM Embedded Raspberry Pi Pico Tutorials]]

Latest revision as of 02:53, 30 December 2021

│ English (en) │

Introduction

UART Interfaces are often used for debugging output, the pico is no exception to this rule.

This application is best tested with picoprobe, when you connect it to your development board as described in the Getting Started Guide chapter then the GPIO pins 0 and 1 are connected to the debug probe which makes them visible as a serial interface on your computer.

Here's again our debugging setup on a breadboard, the picoprobe is on the right, the pico that will run our code is on the left:

picoPicoDebug Steckplatine.png 

program uart;
{$MODE OBJFPC}
{$H+}
{$MEMORY 10000,10000}

uses
  pico_uart_c,
  pico_gpio_c,
  pico_timer_c;
const
  BAUD_RATE=115200;
begin
  gpio_init(TPicoPin.LED);
  gpio_set_dir(TPicoPin.LED,TGPIODirection.GPIO_OUT);
  uart_init(uart0, BAUD_RATE);
  gpio_set_function(TPicoPin.GP0_UART0_TX, TGPIOFunction.GPIO_FUNC_UART);
  gpio_set_function(TPicoPin.GP1_UART0_RX, TGPIOFunction.GPIO_FUNC_UART);
  repeat
    gpio_put(TPicoPin.LED,true);
    uart_puts(uart0, 'Hello, UART!'+#13+#10);
    busy_wait_us_32(500000);
    gpio_put(TPicoPin.LED,false);
    busy_wait_us_32(500000);
  until 1=0;
end.


Connect your terminal program to the UART port and enjoy the message from your Pico. In this example we are using ansistrings, so the $MEMORY setting is important as we will use dynamically allocated AnsiStrings. To visually get confirmation that the app is running we additionally blink the LED on each turn of the main loop.

See also

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