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. | Next peripheral on the list is the UART. | ||
| − | You will now start to find a | + | 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: |
program Blinky; | program Blinky; | ||
| Line 31: | Line 31: | ||
end; | end; | ||
end; | end; | ||
| − | |||
procedure runtime_init; | procedure runtime_init; | ||
const | const | ||
Revision as of 18:55, 31 January 2021
Next peripheral on the list is the UART.
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:
program Blinky;
{$L gpio.c.obj}
{$L uart.c.obj}
{$L clocks.c.obj}
{$L xosc.c.obj}
{$L pll.c.obj}
{$L watchdog.c.obj}
{$L platform.c.obj}
{$LinkLib gcc,static}
procedure clocks_init; external;
procedure gpio_init(gpio : longWord); external;
procedure gpio_set_function(gpio:longWord;fn:longWord); external;
function uart_init(var uart : TUART_Registers; baudrate:longWord) : longWord; external;
function uart_is_writable(var uart : TUART_Registers):boolean;
begin
result := (uart.fr and (1 shl 5)) = 0;
end;
procedure uart_puts(var uart : TUART_Registers; const s : string);
var
i : longWord;
begin
for i := 1 to length(s) do
begin
repeat
until uart_is_writable(uart);
uart.dr := longWord(s[i]);
end;
end;
procedure runtime_init;
const
RESETS_SAFE_BITS= %1111111111100110110111111;
RESETS_PRECLOCK_BITS= %0001111000100110110111110;
RESETS_POSTCLOCK_BITS=%1110000111000000000000001;
begin
resets.reset_set := RESETS_SAFE_BITS;
resets.reset_clr := RESETS_PRECLOCK_BITS;
repeat
until (resets.reset_done and RESETS_PRECLOCK_BITS) = RESETS_PRECLOCK_BITS;
clocks_init;
resets.reset_clr := RESETS_POSTCLOCK_BITS;
repeat
until (resets.reset_done and RESETS_POSTCLOCK_BITS) = RESETS_POSTCLOCK_BITS;
end;
const
BAUD_RATE=115200;
UART_TX_PIN=0;
UART_RX_PIN=1;
GPIO_FUNC_UART=2;
var
i : longWord;
begin
runtime_init;
uart_init(uart0, BAUD_RATE);
gpio_set_function(UART_TX_PIN, GPIO_FUNC_UART);
gpio_set_function(UART_RX_PIN, GPIO_FUNC_UART);
repeat
uart_puts(uart0, 'Hello, UART!'+#13+#10);
for i := 0 to 300000 do ;
until 1=0;
end.
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....
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.
Connect your terminal program to the UART port and enjoy the message from your pico...
