mirror of
https://github.com/espressif/esp-idf.git
synced 2026-04-27 19:13:21 +00:00
Sahil Yadav
112 lines
3.3 KiB
Markdown
112 lines
3.3 KiB
Markdown
| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C5 | ESP32-C6 | ESP32-C61 | ESP32-H2 | ESP32-H4 | ESP32-S3 |
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| ----------------- | ----- | -------- | -------- | -------- | -------- | --------- | -------- | -------- | -------- |
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# NimBLE SPI Slave Receiver Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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## Overview
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This example configures the device as an **SPI slave receiver** and prints received data to UART in hexadecimal format.
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It is intended to work with a peer device acting as an SPI master (for example, a NimBLE BLE Log sender). Data is received on SPI and projected to the serial monitor, which makes this example useful for bring-up and transport validation.
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### What this example does
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- Initializes SPI slave mode (`SPI2_HOST`)
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- Uses MOSI/SCLK/CS lines to receive data in half-duplex style
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- Keeps MISO disabled (`-1`)
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- Receives transactions in 1024-byte DMA buffers
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- Prints received bytes to UART in 32-byte lines (`%02X` format)
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## Hardware behavior
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The receive pins are configured from Kconfig symbols used by this example:
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- `CONFIG_BT_BLE_LOG_SPI_OUT_MOSI_IO_NUM`
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- `CONFIG_BT_BLE_LOG_SPI_OUT_SCLK_IO_NUM`
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- `CONFIG_BT_BLE_LOG_SPI_OUT_CS_IO_NUM`
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Defined in [main/ble_spi_slave.h](main/ble_spi_slave.h).
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The example enables pull-ups on MOSI/SCLK/CS to reduce false activity when no master is connected.
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## Hardware connection
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Connect your SPI master device to the example target:
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- Master MOSI -> Slave MOSI
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- Master SCLK -> Slave SCLK
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- Master CS -> Slave CS
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- GND <-> GND
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Notes:
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- MISO is not used by this example.
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- SPI mode is fixed to mode 0 in current code.
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- Ensure both devices share a common ground.
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## How to Use Example
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Before project configuration and build, set the target:
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```bash
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idf.py set-target <chip_name>
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```
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### Configure the project
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Open configuration menu:
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```bash
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idf.py menuconfig
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```
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Configure SPI pin assignments used by this example via Bluetooth/BLE Log SPI output configuration (MOSI/SCLK/CS), so they match your wiring.
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### Build and flash
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```bash
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idf.py -p PORT flash monitor
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```
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(To exit the serial monitor, type `Ctrl-]`.)
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## Expected output
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When the SPI master sends data, this example prints the received bytes as hexadecimal text, for example:
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```text
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08 00 07 4F 01 00 CC CA 18 00 ...
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```
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Output is line-broken every 32 bytes for readability in the monitor.
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## Typical use with BLE Log pipelines
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This receiver can be used as the SPI-side capture endpoint in BLE Log transport testing:
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1. Master device sends BLE Log frame bytes over SPI.
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2. This example receives and prints them on UART.
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3. Host tools can capture UART hex and decode with BLE log decompression scripts.
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## Limitations
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- This example does not decode BLE payloads; it only receives and prints raw bytes.
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- Transaction buffer size is fixed at 1024 bytes in current source.
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## Troubleshooting
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- **No data printed**
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- Verify wiring and shared ground.
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- Verify pin configuration in menuconfig matches your board wiring.
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- Verify SPI master is actively transmitting and uses mode 0.
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- **Corrupted or unstable output**
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- Check signal integrity and clock speed.
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- Confirm pull-ups and board-level electrical compatibility.
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- **Build errors related to drivers**
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- Ensure SPI/GPIO driver components are enabled (already declared in this example component dependencies).
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