# Tiny 2040 on-board led C programming
**URL:** https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304
**Category:** Support
**Created:** [June 8, 2023, 6:57am UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304 "2023-06-08T06:57:28Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@daneksithethos](https://forums.pimoroni.com/u/daneksithethos)
#### Post date: [June 8, 2023, 6:57am UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/1 "2023-06-08T06:57:28Z")
Hello, I am trying to write the blinke on-board led example for the Tiny 2040. I am using C programming language, and my code is built with CMake.
However NMake gives a LNK1181 error, and a U1077 errors (please note that I was able to make the led blink example work using this as a template [pico-examples/blink.c at master · raspberrypi/pico-examples · GitHub](https://github.com/raspberrypi/pico-examples/blob/master/blink/blink.c)).
I am wondering whether I have to create my own libraries for this project (it seems to me that the problem is in the code somewhere).
I am using this blink example as a template ([pico-examples/blink.c at master · raspberrypi/pico-examples · GitHub](https://github.com/raspberrypi/pico-examples/blob/master/blink/blink.c)).
And I am using this as a reference my include headers ([pico-sdk/pimoroni\_tiny2040.h at master · raspberrypi/pico-sdk · GitHub](https://github.com/raspberrypi/pico-sdk/blob/master/src/boards/include/boards/pimoroni_tiny2040.h)).
Please help me find guidance on how to make my project work ( I am reading this reference [C docs - get started, tutorials, reference. | Microsoft Learn](https://learn.microsoft.com/en-us/cpp/c-language/?view=msvc-170), but I guess I lack knowledge, because I did not find an answer to my question).
---
### Author:  [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)
#### Post date: [June 8, 2023, 8:46am UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/2 "2023-06-08T08:46:57Z")
Just want to confirm, this is a Pimoroni Tiny2040?
I ask because there is also a **Waveshare** RP2040 Tiny.
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### Author:  [@ahnlak](https://forums.pimoroni.com/u/ahnlak)
#### Post date: [June 8, 2023, 11:51am UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/3 "2023-06-08T11:51:16Z")
It’s a little hard to tell without seeing your project files; `LNK1181` is a “file not found” error from the linker, so at a guess I’d say your `CMakeLists.txt` file is probably off - the actual error message text will give you a better idea of exactly where the problem lies.
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### Author:  [@daneksithethos](https://forums.pimoroni.com/u/daneksithethos)
#### Post date: [June 8, 2023, 5:14pm UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/4 "2023-06-08T17:14:03Z")
Yes, it is Pimoroni Tiny 2040.
---
### Author:  [@daneksithethos](https://forums.pimoroni.com/u/daneksithethos)
#### Post date: [June 8, 2023, 5:28pm UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/5 "2023-06-08T17:28:01Z")
Sorry, here are the details:
1. Code from tiny2040\_RGB\_blink.c
```auto
/**
* Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "pico/stdlib.h"
#include
#define _BOARDS_PIMORONI_TINY2040_H
#define PIMORONI_TINY2040_8MB
#define TINY2040_LED_R_PIN 18
#define TINY2040_LED_G_PIN 19
#define TINY2040_LED_B_PIN 20
int main(){
const uint LED_PIN_R = TINY2040_LED_R_PIN;
const uint LED_PIN_G = TINY2040_LED_G_PIN;
const uint LED_PIN_B = TINY2040_LED_B_PIN;
gpio_init(LED_PIN_R);
gpio_init(LED_PIN_G);
gpio_init(LED_PIN_B);
gpio_set_dir(LED_PIN_R, GPIO_OUT);
gpio_set_dir(LED_PIN_G, GPIO_OUT);
gpio_set_dir(LED_PIN_B, GPIO_OUT);
while (true) {
gpio_put(LED_PIN_R, 1);
sleep_ms(250);
gpio_put(LED_PIN_R, 0);
sleep_ms(250);
gpio_put(LED_PIN_G, 1);
sleep_ms(250);
gpio_put(LED_PIN_G, 0);
sleep_ms(250);
gpio_put(LED_PIN_B, 1);
sleep_ms(250);
gpio_put(LED_PIN_B, 0);
sleep_ms(250);
}
}
```
1. CMakeLists.txt
```auto
cmake_minimum_required(VERSION 3.13)
#initialize pico-sdk from GIT
#(note this can come from environment, CMake cache etc.)
set(PICO_SDK_FETCH_FROM_GIT on)
#initialize the SDK based on PICO_SDK_PATH
#note: this must happen before the project()
set(PICO_SDK_PATH $ENV{PICO_SDK_PATH})
include(pico_sdk_import.cmake)
#include(pico_extras_import_optional.cmake)
project(tiny2040_RGB_blink C CXX ASM)
set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)
set(PICO_PICO_BLINK_PATH ${PROJECT_SOURCE_DIR})
#initialize the Raspberry Pi Pico SDK
pico_sdk_init()
//# add url via pico_set_program_url
//# example_auto_set_url(tiny2040_RGB_blink)
add_executable(tiny2040_RGB_blink
tiny2040_RGB_blink.c
)
//# pull in common dependencies
target_link_libraries(tiny2040_RGB_blink pico_stdlib)
//# create map/bin/hex file etc.
pico_add_extra_outputs(tiny2040_RGB_blink)
```
1. Output in Developer Command Prompt after executing ‘nmake’ command
```auto
[1%] Performing build step for 'ELF2UF2Build'
[100%] Built target elf2uf2
[2%] No install step for 'ELF2UF2Build'
[4%] Completed 'ELF2UF2Build'
[11%] Built target ELF2UF2Build
[13%] Building ASM object pico-sdk/src/rp2_common/boot_stage2/CMakeFiles/bs2_default.dir/compile_time_choice.S.obj
cl : Command line warning D9021 : no action performed
[14%] Linking ASM executable bs2_default.elf
Microsoft (R) Incremental Linker Version 14.35.32215.0
Copyright (C) Microsoft Corporation. All rights reserved.
/out:compile_time_choice.S.exe
/out:bs2_default.elf
CMakeFiles\bs2_default.dir\compile_time_choice.S.obj
LINK : fatal error LNK1181: cannot open input file 'CMakeFiles\bs2_default.dir\compile_time_choice.S.obj'
```
Please note that there is also a NMake fatal error U1077 in the output (for some reason it did not write entire output to .txt file after executing nmake \> PATH/TO/OUTPUT.TXT).
---
### Author:  [@daneksithethos](https://forums.pimoroni.com/u/daneksithethos)
#### Post date: [June 8, 2023, 7:43pm UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/6 "2023-06-08T19:43:48Z")
Strangely today after starting VSCode from Developer Comand Prompt (executing ‘code’ command) the project has been built successfully.
Unfortunately I cannot verify if my .uf2 file works as intended because my Tiny 2040 stopped working (does not respond to boot and reset) after I desoldered debug pin headers yesterday.
I would still appreciate any guidance regarding flaws in my project.
---
### Author:  [@hel](https://forums.pimoroni.com/u/hel)
#### Post date: [June 9, 2023, 8:41am UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/7 "2023-06-09T08:41:47Z")
If you enclose code in triple backticks ( ``` ) it stops the forum trying to apply formatting to it and makes everything more readable - I’ve added them into the above post for you :)
---
### Author:  [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)
#### Post date: [June 9, 2023, 9:00am UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/8 "2023-06-09T09:00:46Z")
If you click the **Preformatted Text** option, the \, it sets it all up for you.
---
### Author:  [@daneksithethos](https://forums.pimoroni.com/u/daneksithethos)
#### Post date: [June 9, 2023, 3:53pm UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/9 "2023-06-09T15:53:30Z")
Great, thank you hel!
---
### Author:  [@daneksithethos](https://forums.pimoroni.com/u/daneksithethos)
#### Post date: [June 9, 2023, 3:54pm UTC](https://forums.pimoroni.com/t/tiny-2040-on-board-led-c-programming/22304/10 "2023-06-09T15:54:08Z")
Thank you alphanumeric!