How to Improve ESP-AT Throughput Performance

[中文]

By default, UART is used for communication between ESP-AT and the host MCU, so the maximum throughput speed will not exceed its default configuration, that is, 115200 bps. If users want ESP-AT to achieve high throughput, it is necessary to understand this document and choose the appropriate configuration method. Taking ESP32-C2 as an example, this document introduces how to improve the throughput performance of ESP-AT.

Note

This document describes general methods to improve TCP/UDP/SSL throughput performance when ESP-AT is in Passthrough Mode.

Users could choose one of the following methods to improve throughput performance:

[Simple] Quick Configuration

1. Configure system, LWIP, Wi-Fi parameters

Copy the following code snippet and append to tail of module_config/module_esp32c2_default/sdkconfig.defaults file. For other ESP32-C2 series devices, please modify the sdkconfig.defaults file in the corresponding folder.

# System
CONFIG_ESP_SYSTEM_EVENT_TASK_STACK_SIZE=4096
CONFIG_FREERTOS_UNICORE=n
CONFIG_FREERTOS_HZ=1000
CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_120=y
CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ=120
CONFIG_ESPTOOLPY_FLASHMODE_QIO=y
CONFIG_ESPTOOLPY_FLASHFREQ_60M=y

# LWIP
CONFIG_LWIP_TCP_SND_BUF_DEFAULT=65534
CONFIG_LWIP_TCP_WND_DEFAULT=65534
CONFIG_LWIP_TCP_RECVMBOX_SIZE=12
CONFIG_LWIP_UDP_RECVMBOX_SIZE=12
CONFIG_LWIP_TCPIP_RECVMBOX_SIZE=64

# Wi-Fi
CONFIG_ESP32_WIFI_STATIC_RX_BUFFER_NUM=16
CONFIG_ESP32_WIFI_DYNAMIC_RX_BUFFER_NUM=64
CONFIG_ESP32_WIFI_DYNAMIC_TX_BUFFER_NUM=64
CONFIG_ESP32_WIFI_TX_BA_WIN=32
CONFIG_ESP32_WIFI_RX_BA_WIN=32
CONFIG_ESP32_WIFI_AMPDU_TX_ENABLED=y
CONFIG_ESP32_WIFI_AMPDU_RX_ENABLED=y

2. Enlarge UART buffer size

Copy the following code snippet and replace the uart_driver_install() line of at_uart_task.c file.

uart_driver_install(esp_at_uart_port, 1024 * 16, 1024 * 16, 100, &esp_at_uart_queue, 0);

3. Delete, Build, Flash, Run

rm -rf build sdkconfig
./build.py build
./build.py flash monitor

4. Increase UART baud rate before entering passthrough mode

A typical ESP-AT commands sequence is as follows:

AT+CWMODE=1
AT+CWJAP="ssid","password"
AT+UART_CUR=3000000,8,1,0,3
AT+CIPSTART="TCP","192.168.105.13",3344
AT+CIPMODE=1
AT+CIPSEND
// data transmission

This simple and quick configuration method can improve the throughput to a certain extent, but sometimes it might not meet the expectations of users. In addition, some configurations may not hit the bottleneck of throughput. Higher configurations may sacrifice memory resources or power consumption. Therefore, users could also familiarize themselves with the following recommended method and make the precise configuration.