Espressif Systems ESP - Page 146

Chapter 4. Software framework
4.10.16 How does ESP32 adjust Wi-Fi TX power?
• Con󰝘gure Component config > PHY > Max Wi-Fi TX power(dBm) via menucon󰝘g, and the max
value is 20 dBm.
• Use API esp_err_t esp_wi_set_max_tx_power(int8_t power);.
4.10.17 [Connect] How many devices is ESP32 able to connect in AP mode?
Up to 10 devices in AP mode. It is con󰝘gured to support four devices by default.
4.10.18 [Connect] How do Wi-Fi modules rank signal strength levels based on RSSI val-
ues？
We do not have a rating for RSSI signal strength. You can take the calculation method from Android
system for reference if you need a standard for classi󰝘cation.
@UnsupportedAppUsage
private static final int MIN_RSSI = -100;
/** Anything better than or equal to this will show the max bars. */
@UnsupportedAppUsage
private static final int MAX_RSSI = -55;
public static int calculateSignalLevel(int rssi, int numLevels) {
if(rssi <= MIN_RSSI) {
return 0;
} else if (rssi >= MAX_RSSI) {
return numLevels - 1;
} else {
float inputRange = (MAX_RSSI -MIN_RSSI);
float outputRange = (numLevels - 1);
return (int)((float)(rssi - MIN_RSSI) * outputRange / inputRange);
}
}
4.10.19 [Connect] Why does ESP32 disconnect from STA when it is in Soft-AP mode?
• By default, the ESP32 will disconnect from the connected STA if it doesn’t receive any data from this STA
for continuous 5 minutes. This time can be modi󰝘ed via API esp_wi󰝘_set_inactive_time.
• Note: esp_wi󰝘_set_inactive_time is a newly added API.
– master commit: 63b566eb27da187c13f9b6ef707ab3315da24c9d
– 4.2 commit: d0dae5426380f771b0e192d8ccb051ce5308485e
– 4.1 commit: 445635fe45b7205497ad81289c5a808156a43539
– 4.0 commit: 0a8abf6ffececa37538f7293063dc0b50c72082a
– 3.3 commit: 908938bc3cd917edec2ed37a709a153182d511da
Espressif Systems 129
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