(FE310::ClockId::coreclk), CORECLK_FREQ_Hz);
for(;;)
{
led_blue.set();
delay.delay_ms(250);
led_blue.clr();
delay.delay_ms(250);
}
return 0;
}
```
For a full working example take a look [here](https://github.com/snowfox-project/snowfox-examples/blob/master/hal/FE310/hal-fe310-digital-out-pin/hal-fe310-digital-out-pin.cpp).
If you want to compile it for your HiFive 1 Rev. B you’ve got to follow the following steps:
- Download/Install RISCV64 Compiler (you probably already did that)
```bash
sudo wget https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.2.0-2019.02.0-x86_64-linux-ubuntu14.tar.gz
sudo tar -xzvf riscv64-unknown-elf-gcc-8.2.0-2019.02.0-x86_64-linux-ubuntu14.tar.gz
export PATH=$PATH:/opt/riscv64-unknown-elf-gcc-8.2.0-2019.02.0-x86_64-linux-ubuntu14/bin
```
- Clone the Snowfox Repository with all examples
```bash
git clone --recurse-submodules https://github.com/snowfox-project/snowfox.git
cd snowfox
```
- Build the SiFive FE310-G002 GPIO example (the compiled binary is located in `build/bin/hal-fe310-digital-out-pin )
```bash
.ci/script/run-build-example.sh examples/hal/FE310/hal-fe310-digital-out-pin
```
As for getting the number of a specific pin exposed on the HiFive 1 Rev. B header - you can look up the exact GPIO number by taking a look at the [schematic](https://sifive.cdn.prismic.io/sifive%2Fa4546ced-0922-4d87-9334-e97c1a9fd9a5_hifive1.b01.schematics.pdf) / page 3. It would be an easy thing to create a header file containing constants for each GPIO pin exposed on a header, e.g.
```auto
/* ... */
enum class HiFive1RevBGpioPin : uint32_t
{
D2 = 18, /* GPIO_18 */
D3 = 19, /* GPIO_19 */
/* etc. */
};
/* ... */
```
[Pull requests](https://github.com/snowfox-project/snowfox/pulls) are always welcome 😉
---
### Author:  [@Jonas](https://forums.sifive.com/u/Jonas)
#### Post date: [May 14, 2020, 9:48pm UTC](https://forums.sifive.com/t/interfacing-with-the-pins/3631/3 "2020-05-14T21:48:36Z")
It’s interesting. I actually imported these as source files in scifive to see if the libraries would work in the IDE. The only problem seems to be that the code above is written in c++ rather than C. Does snowfox support C? I think that’s all I would need. Granted, I haven’t tried it the way you suggested. I’m not complainin, I’m just curious.
---
### Author:  [@al3x](https://forums.sifive.com/u/al3x)
#### Post date: [May 15, 2020, 4:17am UTC](https://forums.sifive.com/t/interfacing-with-the-pins/3631/4 "2020-05-15T04:17:57Z")
Hi Jonas 👋 You’ll be definitely able to integrate Snowfox code within the Freedom SDK / Studio (and compile them) but I doubt it’s the wisest course of action. Both Freedom SDK and Snowfox provide HAL (Hardware Abstraction Layer) functionality but each of those projects is self-contained and follows its own design philosophy. Wildly mixing together without knowing what you are doing is a guarantee for a headache 😉
---
### Author:  [@Jonas](https://forums.sifive.com/u/Jonas)
#### Post date: [May 15, 2020, 4:29am UTC](https://forums.sifive.com/t/interfacing-with-the-pins/3631/5 "2020-05-15T04:29:10Z")
Noted. Naturally, I like working within a GUI workspace because of all the tools and convenience, but I will give your advice a try in the terminal.
---
### Author:  [@al3x](https://forums.sifive.com/u/al3x)
#### Post date: [May 15, 2020, 5:23am UTC](https://forums.sifive.com/t/interfacing-with-the-pins/3631/6 "2020-05-15T05:23:29Z")
Hi Jonas 👋
I can understand your reluctance to deviate from GUI tools because I myself like to work with a good GUI when its available. Fortunately the HiFive 1 Rev. B is supported by [Segger Ozone](https://www.segger.com/products/development-tools/ozone-j-link-debugger/) which is one of the best debugging IDEs that’s around. In order to get started you have to:
- Download & Install [Ozone](https://www.segger.com/downloads/jlink/#Ozone)
- Start it up and select the FE310 MCU
- Connect the HiFive 1 Rev. B and check if the JLink on the HiFive is detected
- Select the binary file for upload/debugging ( `snowfox/build/bin/hal-fe310-digital-out-pin` )
- Download binary via `Download & Reset Programm` and perform a reset and halt in order to start debugging from the very beginning via `Reset & Halt`
Have fun 😉