Espressif ESP32-S2 User Manual

Chapter 4. API Guides
received Wi-Fi data can be delayed for as long as the DTIM period (minimum power save mode) or the listen inter-
val (maximum power save mode). Disabling modem sleep entirely is not possible for Wi-Fi and Bluetooth coexist
mode.
The default Modem-sleep mode is WIFI_PS_MIN_MODEM.
AP Sleep
Currently ESP32-S2 AP doesn’t support all of the power save feature defined in Wi-Fi specification. To be specific,
the AP only caches unicast data for the stations connect to this AP, but doesn’t cache the multicast data for the
stations. If stations connected to the ESP32-S2 AP are power save enabled, they may experience multicast packet
loss.
In the future, all power save features will be supported on ESP32-S2 AP.
4.33.20 ESP32-S2 Wi-Fi Throughput
The table below shows the best throughput results we got in Espressif’s lab and in a shield box.
Type/Throughput Air In Lab Shield-box Test Tool IDF Version (commit ID)
Raw 802.11 Packet RX N/A 130 MBit/s Internal tool NA
Raw 802.11 Packet TX N/A 130 MBit/s Internal tool NA
UDP RX 30 MBit/s 70 MBit/s iperf example 15575346
UDP TX 30 MBit/s 50 MBit/s iperf example 15575346
TCP RX 20 MBit/s 32 MBit/s iperf example 15575346
TCP TX 20 MBit/s 37 MBit/s iperf example 15575346
When the throughput is tested by iperf example, the sdkconfig is examples/wifi/iperf/sdkconfig.defaults.esp32s2.
4.33.21 Wi-Fi 80211 Packet Send
The esp_wifi_80211_tx() API can be used to:
• Send the beacon, probe request, probe response, action frame.
• Send the non-QoS data frame.
It cannot be used for sending encrypted or QoS frames.
Preconditions of Using esp_wifi_80211_tx()
• The Wi-Fi mode is Station, or AP, or Station+AP.
• Either esp_wifi_set_promiscuous(true), or esp_wifi_start(), or both of these APIs return ESP_OK.
This is because we need to make sure that Wi-Fi hardware is initialized before esp_wifi_80211_tx()
is called. In ESP32-S2, both esp_wifi_set_promiscuous(true) and esp_wifi_start() can trigger the
initialization of Wi-Fi hardware.
• The parameters of esp_wifi_80211_tx() are hereby correctly provided.
Data rate
• If there is no Wi-Fi connection, the data rate is 1 Mbps.
• If there is Wi-Fi connection and the packet is from station to AP or from AP to station, the data rate is same
as the Wi-Fi connection. Otherwise the data rate is 1 Mbps.
Espressif Systems 1540
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Release v4.4

Espressif ESP32-S2 Specifications

General

Brand	Espressif
Model	ESP32-S2
Category	Single board computers
Language	English