├── prj.conf ├── .gitignore ├── assets ├── analog.jpg ├── logo.jpg └── digital.jpg ├── CMakeLists.txt ├── boards └── nrf5340dk_nrf5340_cpuapp.overlay ├── README.md ├── src └── main.c └── LICENSE /prj.conf: -------------------------------------------------------------------------------- 1 | CONFIG_I2S=y -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | .DS_Store 2 | ._.DS_Store 3 | **/.DS_Store 4 | **/._.DS_Store 5 | build*/** -------------------------------------------------------------------------------- /assets/analog.jpg: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/GatCode/NordicAudioWave/HEAD/assets/analog.jpg -------------------------------------------------------------------------------- /assets/logo.jpg: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/GatCode/NordicAudioWave/HEAD/assets/logo.jpg -------------------------------------------------------------------------------- /assets/digital.jpg: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/GatCode/NordicAudioWave/HEAD/assets/digital.jpg -------------------------------------------------------------------------------- /CMakeLists.txt: -------------------------------------------------------------------------------- 1 | cmake_minimum_required(VERSION 3.20.0) 2 | 3 | find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE}) 4 | project(NordicAudioWave) 5 | 6 | target_sources(app PRIVATE src/main.c) 7 | -------------------------------------------------------------------------------- /boards/nrf5340dk_nrf5340_cpuapp.overlay: -------------------------------------------------------------------------------- 1 | // https://docs.zephyrproject.org/2.6.0/reference/devicetree/bindings/i2s/nordic%2Cnrf-i2s.html#dtbinding-nordic-nrf-i2s 2 | &pinctrl { 3 | i2s0_default_alt: i2s0_default_alt { 4 | group1 { 5 | psels = , 6 | , 7 | , 8 | ; 9 | }; 10 | }; 11 | }; 12 | 13 | &clock { 14 | hfclkaudio-frequency = <11289600>; 15 | }; 16 | 17 | i2s_rxtx: &i2s0 { 18 | status = "okay"; 19 | pinctrl-0 = <&i2s0_default_alt>; 20 | pinctrl-names = "default"; 21 | clock-source = "ACLK"; 22 | }; 23 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 |

2 | 3 |

4 | 5 | 6 | 7 |

8 |

9 | 10 | ## About 11 | Since at this point in time, there is very little information available on how to use a [nrf5340dk board](https://www.nordicsemi.com/Products/Development-hardware/nRF5340-DK/GetStarted?lang=en) in combination with an I2S DAC chip ([Adafruit I2S Stereo Decoder - UDA1334A](https://www.adafruit.com/product/3678) in my case), the code in this repository will give you a brief overview on how you can achieve this goal. 12 | 13 | This sample is based on the [Zephyr I2S testcases](https://github.com/anangl/zephyr/tree/16a1c81d6f2becbf561a615337de8ba65af31533/tests/drivers/i2s/i2s_api/src) (copied sine wave data_frame table), as well as the [I2S Echo sample](https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/drivers/i2s/echo). Please take a look at these samples if you want to get further information on how you can use the I2S driver itself. 14 | 15 | Furthermore, the concrete API definitions can be found [here](https://docs.zephyrproject.org/latest/reference/audio/i2s.html). 16 | 17 | ## Basic principle 18 | To be able to talk to I2S devices, one has to follow (more or less) the following steps: 19 | - **Step 1**: Get the I2S device from the [devicetree](https://docs.zephyrproject.org/latest/guides/dts/howtos.html#use-devicetree-overlays) 20 | - **Step 2**: Allocate a [memory slab](https://docs.zephyrproject.org/latest/reference/kernel/memory/slabs.html) 21 | - **Step 3**: Configure the I2S device 22 | - **Step 4**: Allocate memory blocks in the memory slab 23 | - **Step 5**: Trigger the start of the data transmission 24 | - **Step 6**: Fill the memory blocks with your data (e.g. sine wave) 25 | - **Step 7**: Use `i2s_trigger(...)` to write the data to the I2S device 26 | 27 | All of these steps are explained in greater detail inside the `main.c` file itself! 28 | 29 | ## Result of the sample code 30 | If you flash the sample code to a bare nrf5340dk board and probe the pins `P1.15` (`47` in the overlay) and `P1.13` (`45` in the overlay), you can see that the chip generates a nice clock signal (blue trace) and the corresponsing the data signal (yellow trace). 31 | 32 |

33 | 34 | If you now attach the DAC board to the nrf5340 board, you should see the corresponding analog output: 35 | 36 |

37 | 38 | 🎉 we successfully created an analog signal on an I2S DAC chip! 39 | 40 | ## Limitations 41 | 42 | This Software is provided as-is! 43 | 44 | Please feel free to adapt it to your needs and contribute to the project. I would be very grateful to include your improvements. Thanks for your support! 45 | 46 | **WARNING:** Everyone is responsible for what he/she is doing! I am not responsible if you hurt yourself, torch your house or anything that kind trying to do build something new! You are doing everything at your own risk! 47 | -------------------------------------------------------------------------------- /src/main.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | #include 7 | 8 | /* Prepare for 32 sample values */ 9 | #define NUM_SAMPLES 32 10 | 11 | /* Sine Wave Sample */ 12 | static int16_t data_frame[NUM_SAMPLES] = { 13 | 6392, 12539, 18204, 23169, 27244, 30272, 32137, 32767, 32137, 14 | 30272, 27244, 23169, 18204, 12539, 6392, 0, -6393, -12540, 15 | -18205, -23170, -27245, -30273, -32138, -32767, -32138, -30273, -27245, 16 | -23170, -18205, -12540, -6393, -1, 17 | }; 18 | 19 | /* The size of the memory block should be a multiple of data_frame size */ 20 | #define BLOCK_SIZE (2 * sizeof(data_frame)) 21 | 22 | /* The number of memory blocks in a slab has to be at least 2 per queue */ 23 | #define NUM_BLOCKS 5 24 | 25 | /* Define a new Memory Slab which consistes of NUM_BLOCKS blocks 26 | __________________________________________________________________________ 27 | | Block 0 | Block 1 | Block 2 | Block 3 | Block 4 | 28 | | 0...31 | 0...31 | 0...31 | 0...31 | 0...31 | 29 | |______________|______________|______________|______________|______________| 30 | */ 31 | static K_MEM_SLAB_DEFINE(mem_slab, BLOCK_SIZE, NUM_BLOCKS, NUM_SAMPLES); 32 | 33 | void main(void) { 34 | /* Get I2S device from the devicetree */ 35 | const struct device *i2s_dev = DEVICE_DT_GET(DT_NODELABEL(i2s_rxtx)); 36 | if (!device_is_ready(i2s_dev)) { 37 | printk("%s is not ready\n", i2s_dev->name); 38 | return; 39 | } 40 | 41 | /* Configure the I2S device */ 42 | struct i2s_config i2s_cfg; 43 | i2s_cfg.word_size = 16; // due to int16_t in data_frame declaration 44 | i2s_cfg.channels = 2; // L + R channel 45 | i2s_cfg.format = I2S_FMT_DATA_FORMAT_I2S; 46 | i2s_cfg.options = I2S_OPT_BIT_CLK_MASTER | I2S_OPT_FRAME_CLK_MASTER; 47 | i2s_cfg.frame_clk_freq = 44100; 48 | i2s_cfg.mem_slab = &mem_slab; 49 | i2s_cfg.block_size = BLOCK_SIZE; 50 | i2s_cfg.timeout = 1000; 51 | int ret = i2s_configure(i2s_dev, I2S_DIR_TX, &i2s_cfg); 52 | if (ret < 0) { 53 | printk("Failed to configure the I2S stream: (%d)\n", ret); 54 | return; 55 | } 56 | 57 | /* Allocate the memory blocks (tx buffer) from the slab and 58 | set everything to 0 */ 59 | void *mem_blocks; 60 | ret = k_mem_slab_alloc(&mem_slab, &mem_blocks, K_NO_WAIT); 61 | if (ret < 0) { 62 | printk("Failed to allocate the memory blocks: %d\n", ret); 63 | return; 64 | } 65 | memset((uint16_t*)mem_blocks, 0, NUM_SAMPLES * NUM_BLOCKS); 66 | 67 | /* Start the transmission of data */ 68 | ret = i2s_trigger(i2s_dev, I2S_DIR_TX, I2S_TRIGGER_START); 69 | if (ret < 0) { 70 | printk("Failed to start the transmission: %d\n", ret); 71 | return; 72 | } 73 | 74 | for(;;) { 75 | /* Put data into the tx buffer */ 76 | for (int i = 0; i < NUM_SAMPLES * NUM_BLOCKS; i++) { 77 | ((uint16_t*)mem_blocks)[i] = data_frame[i % NUM_SAMPLES]; 78 | } 79 | 80 | /* Write Data */ 81 | int ret = i2s_buf_write(i2s_dev, mem_blocks, BLOCK_SIZE); 82 | if (ret < 0) { 83 | printk("Error: i2s_write failed with %d\n", ret); 84 | return; 85 | } 86 | } 87 | } 88 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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