79 lines
4.9 KiB
Markdown
79 lines
4.9 KiB
Markdown
# Get Started Examples
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[[中文]](./README_cn.md)
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This example demonstrates how to obtain CSI data through communication between two espressif chips, and uses a graphical interface to display real-time data of CSI subcarriers
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## hardware
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You need to prepare two development boards for espressif chips, one as the sender and the other as the receiver
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1. Use ESP32-C5 / ESP32-C6: ESP32-C5 supports dual-band Wi-Fi communication and is one of the best RF chips available. ESP32-C6 is the best RF chip among the currently released models.
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2. Use an external antenna: The PCB antenna has poor directivity and is easily interfered with by the motherboard.
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3. The distance between the two devices should be greater than 1 meter.
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## Binding
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1. Burn the firmware of `csi_recv` and `csi_send` on two development boards respectively
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```shell
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# csi_send
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cd esp-csi/examples/get-started/csi_send
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idf.py set-target esp32c3
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idf.py flash -b 921600 -p /dev/ttyUSB0 monitor
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# csi_recv
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cd esp-csi/examples/get-started/csi_recv
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idf.py set-target esp32c3
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idf.py flash -b 921600 -p /dev/ttyUSB1
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```
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2. Run `csi_data_read_parse.py` in `csi_recv` for data analysis. Please close `idf.py monitor` before running
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```shell
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cd esp-csi-gitlab/examples/get-started/tools
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# Install python related dependencies
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pip install -r requirements.txt
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# Graphical display
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python csi_data_read_parse.py -p /dev/ttyUSB1
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```
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## CSI Data Format
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Taking a line of CSI raw data as an example:
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> type,id,mac,rssi,rate,sig_mode,mcs,bandwidth,smoothing,not_sounding,aggregation,stbc,fec_coding,sgi,noise_floor,ampdu_cnt,channel,secondary_channel,local_timestamp,ant,sig_len,rx_state,len,first_word,data
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CSI_DATA,0,94:d9:b3:80:8c:81,-30,11,1,6,1,0,1,0,1,0,0,-93,0,13,2,2751923,0,67,0,128,1,"[67,48,4,0,0,0,0,0,0,0,5,0,20,1,20,1,19,0,17,1,16,2,15,2,14,1,12,0,12,-1,12,-3,12,-4,13,-6,15,-7,16,-8,16,-8,16,-8,16,-6,15,-5,15,-4,14,-4,13,-4,12,-4,11,-4,10,-4,9,-5,8,-6,4,-4,8,-9,9,-10,9,-10,10,-11,11,-10,11,-10,12,-9,11,-8,11,-7,10,-6,9,-6,7,-6,6,-7,5,-7,5,-8,5,-9,5,-10,5,-11,5,-11,6,-11,7,-11,8,-11,9,-10,9,-9,8,-8,8,-7,1,-2,0,0,0,0,0,0,0,0]"
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*ESP32-C5 and ESP32-C6 are:*
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>type,seq,mac,rssi,rate,noise_floor,fft_gain,agc_gain,channel,local_timestamp,sig_len,rx_state,len,first_word,data
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CSI_DATA,7,1a:00:00:00:00:00,-23,11,-96,32,4,11,372852,47,0,256,0,"[0,0,0,0,0,0,0,0,0,0,0,0,-6,-13,-6,-14,-3,-15,-2,-16,-2,-18,-3,-17,-1,-18,2,-19,0,-21,3,-21,1,-20,4,-21,4,-23,6,-22,7,-21,8,-23,9,-23,10,-21,10,-22,11,-20,12,-19,11,-25,13,-22,12,-23,14,-23,14,-22,14,-21,13,-21,13,-19,14,-22,14,-19,14,-23,16,-22,14,-22,13,-22,14,-21,13,-22,13,-23,13,-23,12,-26,13,-24,13,-24,12,-25,14,-29,13,-26,14,-26,15,-26,13,-27,15,-28,16,-27,14,-30,15,-28,16,-28,18,-27,16,-31,18,-31,19,-31,0,0,0,0,0,0,-29,-23,-28,-21,-30,-18,-26,-20,-30,-21,-25,-23,-26,-21,-25,-22,-26,-19,-22,-22,-24,-19,-22,-20,-24,-20,-24,-18,-23,-18,-22,-18,-25,-17,-23,-18,-21,-18,-21,-17,-24,-14,-22,-16,-21,-14,-22,-15,-21,-19,-23,-16,-22,-17,-23,-13,-23,-16,-25,-15,-21,-17,-22,-15,-21,-17,-23,-16,-20,-16,-21,-20,-21,-19,-21,-19,-19,-20,-17,-20,-18,-20,-16,-21,-15,-21,-15,-20,-13,-21,-11,-20,-10,-20,-11,-19,-9,-20,-8,-22,-6,-19,-7,-20,-4,-19,-2,-18,-2,-18,1,-17,4,-18,0,0,0,0,0,0,0,0,0,0]"
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- **Metadata Fields**: Including type, id, mac, rssi, rate, ... len, first_word, etc.
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- **CSI Data**: Stored in the last item data array, enclosed in [...]. It contains the channel state information for each subcarrier. For detailed structure, refer to the Long Training Field (LTF) section of the [ESP-WIFI-CSI Guide](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/wifi.html#wi-fi-channel-state-information). For each subcarrier, the imaginary part is stored first, followed by the real part (i.e., [Imaginary part of subcarrier 1, Real part of subcarrier 1, Imaginary part of subcarrier 2, Real part of subcarrier 2, Imaginary part of subcarrier 3, Real part of subcarrier 3, ...]).
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The order of LTF is: LLTF, HT-LTF, STBC-HT-LTF. Depending on the channel and grouping information, not all 3 LTFs may appear.
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## A&Q
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### 1. `csi_send` prints no memory
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- **Phenomenon**: The following log appears on the serial port:
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```shell
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W (510693) csi_send: <ESP_ERR_ESPNOW_NO_MEM> ESP-NOW send error
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````
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- **Reason**: The current channel is congested causing congestion in sending packets, so that the ESP-NOW buffer space is full
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- **Solution**: Change the Wi-Fi channel or change to a place with a better network environment
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### 2. `csi_data_read_parse.py` Serial port printing exception
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- **Phenomenon**: The following log appears on the serial port:
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```shell
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element number is not equal
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data is not incomplete
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````
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- **Reason**: PYQT takes up a lot of CPU when drawing, causing the PC to be unable to read the serial port buffer queue in time, resulting in data confusion
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- **Solution**: Advance the baud rate of the serial port
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