トップ > ESP32 > M5Stackの電池延命化と低電力化

M5Stackの電池延命化と低電力化

ESP32 M5Stack WiFi 2.マイコン

目次

チャージコントローラによる充電量の制限

M5Stackの充電制御IC IP5306のネット上に分散していたレジスタ情報をまとめる 様によると、「M5Stack BASICのボトム(LiPo:110mAh)を使うときは、スケッチのsetup()の最初に以下のように記載してやることで、充電電流オーバーによるLiPoの劣化をある程度防げるはず」との記載。

setup(){
  M5.begin();
  M5.Power.begin();
  M5.Power.setVinMaxCurrent(CURRENT_100MA) ;

一つの可能性に行きついたが、太陽光パネルをM5Stackに接続した場合、チャージコントローラであるIP5306が過充電・放電を防いでくれるのではないか。 つまり、外部にチャージコントローラは不要になるのではないか

M5StickCのAXP192の電源周りを調べる | Lang-ship によると、M5StickCのチャージコントロータAXP192では、

  • USB INはデフォルトで500mAに制限されている(レジスタ値変更により、更に制限できる可能性もある)

  • AXP192経由での過放電は禁止されている(と推測されている)

  • 過電圧保護回路が入っている。

    外部電源電圧が6.3Vを超えると、APX19xはIRQ1 / 4を送信し、外部電源が過電圧であることを示します。外部電源が7Vを超えると、AXP192は自動的にシャットダウンします。 M5-Schematic/AXP192 Datasheet v1.13_cn.pdf at master · m5stack/M5-Schematic · GitHub

低電力化

M5StickCでの省電力ノウハウ | Lang-ship によると、画面有り・WiFiありで消費電力を最小にするには、

  1. ESP32 80MHz(無線利用) で15.4mA
  2. 画面8以下で 1.0mA

の電流設定が良いと想定する。更にWiFiの消費電力を下げるには、下記が必要。

  • 無線送信電力を100mW(20dBm)から50mW(17dBm)、10mW(10dBm)へ下げる
  • APモードの場合、ビーコン間隔を最長

esp-idf/esp_wifi.h at 1c7a8b3b712c4020562551f692d0ced8f7470d2c · espressif/esp-idf · GitHubより、 ESP32のソースコードで電力や通信レート・距離、チャネルに関連する関数を抜粋しておく。

WiFiの場合

esp_err_t esp_wifi_set_ps(wifi_ps_type_t type);
esp_err_t esp_wifi_get_ps(wifi_ps_type_t *type);
//The default protocol is (WIFI_PROTOCOL_11B|WIFI_PROTOCOL_11G|WIFI_PROTOCOL_11N)
esp_err_t esp_wifi_set_bandwidth(wifi_interface_t ifx, wifi_bandwidth_t bw);
//@attention 2. WIFI_BW_HT40 is supported only when the interface support 11N
esp_err_t esp_wifi_set_vendor_ie_cb(esp_vendor_ie_cb_t cb, void *ctx);
  *            Level0 represents highest transmiting power and level5 represents lowest
  *            transmiting power. 
  *            levels as follows:
  *            - [78, 127]: level0 //20dBm??
  *            - [76, 77]: level1
  *            - [74, 75]: level2
  *            - [68, 73]: level3
  *            - [60, 67]: level4
  *            - [52, 59]: level5
  *            - [44, 51]: level5 - 2dBm
  *            - [34, 43]: level5 - 4.5dBm
  *            - [28, 33]: level5 - 6dBm
  *            - [20, 27]: level5 - 8dBm
  *            - [8, 19]: level5 - 11dBm
  *            - [-128, 7]: level5 - 14dBm

esp_err_t esp_wifi_set_ant_gpio(const wifi_ant_gpio_config_t *config);

/**
  * @brief     Set primary/secondary channel of ESP32
  *
  * @attention 1. This API should be called after esp_wifi_start()
  * @attention 2. When ESP32 is in STA mode, this API should not be called when STA is scanning or connecting to an external AP
  * @attention 3. When ESP32 is in softAP mode, this API should not be called when softAP has connected to external STAs
  * @attention 4. When ESP32 is in STA+softAP mode, this API should not be called when in the scenarios described above
  *
  * @param     primary  for HT20, primary is the channel number, for HT40, primary is the primary channel
  * @param     second   for HT20, second is ignored, for HT40, second is the second channel
  *
  * @return
  *    - ESP_OK: succeed
  *    - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init
  *    - ESP_ERR_WIFI_IF: invalid interface
  *    - ESP_ERR_INVALID_ARG: invalid argument
  */
esp_err_t esp_wifi_set_channel(uint8_t primary, wifi_second_chan_t second);



/**
  * @brief     configure country info
  *
  * @attention 1. It is discouraged to call this API since this doesn't validate the per-country rules,
  *               it's up to the user to fill in all fields according to local regulations.
  *               Please use esp_wifi_set_country_code instead.
  * @attention 2. The default country is CHINA {.cc="CN", .schan=1, .nchan=13, policy=WIFI_COUNTRY_POLICY_AUTO}
  * @attention 3. When the country policy is WIFI_COUNTRY_POLICY_AUTO, the country info of the AP to which
  *               the station is connected is used. E.g. if the configured country info is {.cc="USA", .schan=1, .nchan=11}
  *               and the country info of the AP to which the station is connected is {.cc="JP", .schan=1, .nchan=14}
  *               then the country info that will be used is {.cc="JP", .schan=1, .nchan=14}. If the station disconnected
  *               from the AP the country info is set back to the country info of the station automatically,
  *               {.cc="US", .schan=1, .nchan=11} in the example.
  * @attention 4. When the country policy is WIFI_COUNTRY_POLICY_MANUAL, then the configured country info is used always.
  * @attention 5. When the country info is changed because of configuration or because the station connects to a different
  *               external AP, the country IE in probe response/beacon of the soft-AP is also changed.
  * @attention 6. The country configuration is stored into flash.
  * @attention 7. When this API is called, the PHY init data will switch to the PHY init data type corresponding to the
  *               country info.
  *
  * @param     country   the configured country info
  *
  * @return
  *    - ESP_OK: succeed
  *    - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init
  *    - ESP_ERR_INVALID_ARG: invalid argument
  */
esp_err_t esp_wifi_set_country(const wifi_country_t *country);


/**
  * @brief     Set maximum transmitting power after WiFi start.
  *
  * @attention 1. Maximum power before wifi startup is limited by PHY init data bin.
  * @attention 2. The value set by this API will be mapped to the max_tx_power of the structure wifi_country_t variable.
  * @attention 3. Mapping Table {Power, max_tx_power} = {{8,   2}, {20,  5}, {28,  7}, {34,  8}, {44, 11},
  *                                                      {52, 13}, {56, 14}, {60, 15}, {66, 16}, {72, 18}, {80, 20}}.
  * @attention 4. Param power unit is 0.25dBm, range is [8, 84] corresponding to 2dBm - 20dBm.
  * @attention 5. Relationship between set value and actual value. As follows: {set value range, actual value} = {{[8,  19],8}, {[20, 27],20}, {[28, 33],28}, {[34, 43],34}, {[44, 51],44}, {[52, 55],52}, {[56, 59],56}, {[60, 65],60}, {[66, 71],66}, {[72, 79],72}, {[80, 84],80}}.
  *
  * @param     power  Maximum WiFi transmitting power.
  *
  * @return
  *    - ESP_OK: succeed
  *    - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init
  *    - ESP_ERR_WIFI_NOT_START: WiFi is not started by esp_wifi_start
  *    - ESP_ERR_WIFI_ARG: invalid argument, e.g. parameter is out of range
  */
esp_err_t esp_wifi_set_max_tx_power(int8_t power);


/**
 * @brief      Get the TSF time
 *             In Station mode or SoftAP+Station mode if station is not connected or station doesn't receive at least
 *             one beacon after connected, will return 0
 *
 * @attention  Enabling power save may cause the return value inaccurate, except WiFi modem sleep
 *
 * @param      interface The interface whose tsf_time is to be retrieved.
 *
 * @return     0 or the TSF time
 */
int64_t esp_wifi_get_tsf_time(wifi_interface_t interface);


/**
  * @brief     Set the inactive time of the ESP32 STA or AP
  *
  * @attention 1. For Station, If the station does not receive a beacon frame from the connected SoftAP during the inactive time,
  *               disconnect from SoftAP. Default 6s.
  * @attention 2. For SoftAP, If the softAP doesn't receive any data from the connected STA during inactive time,
  *               the softAP will force deauth the STA. Default is 300s.
  * @attention 3. The inactive time configuration is not stored into flash
  *
  * @param     ifx  interface to be configured.
  * @param     sec  Inactive time. Unit seconds.
  *
  * @return
  *    - ESP_OK: succeed
  *    - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init
  *    - ESP_ERR_WIFI_NOT_STARTED: WiFi is not started by esp_wifi_start
  *    - ESP_ERR_WIFI_ARG: invalid argument, For Station, if sec is less than 3. For SoftAP, if sec is less than 10.
  */
esp_err_t esp_wifi_set_inactive_time(wifi_interface_t ifx, uint16_t sec);


/**
  * @brief      Enable or disable 11b rate of specified interface
  *
  * @attention  1. This API should be called after esp_wifi_init() and before esp_wifi_start().
  * @attention  2. Only when really need to disable 11b rate call this API otherwise don't call this.
  *
  * @param      ifx  Interface to be configured.
  * @param      disable true means disable 11b rate while false means enable 11b rate.
  *
  * @return
  *    - ESP_OK: succeed
  *    - others: failed
  */
esp_err_t esp_wifi_config_11b_rate(wifi_interface_t ifx, bool disable);

/**
  * @brief      Config ESPNOW rate of specified interface
  *
  * @attention  1. This API should be called after esp_wifi_init() and before esp_wifi_start().
  *
  * @param      ifx  Interface to be configured.
  * @param      rate Phy rate to be configured.
  *
  * @return
  *    - ESP_OK: succeed
  *    - others: failed
  */
esp_err_t esp_wifi_config_espnow_rate(wifi_interface_t ifx, wifi_phy_rate_t rate);

/**
  * @brief      Set interval for station to wake up periodically at disconnected.
  *
  * @attention 1. Only when ESP_WIFI_STA_DISCONNECTED_PM_ENABLE is enabled, this configuration could work
  * @attention 2. This configuration only work for station mode and disconnected status
  * @attention 3. This configuration would influence nothing until some module configure wake_window
  * @attention 4. A sensible interval which is not too small is recommended (e.g. 100ms)
  *
  * @param      interval  how much micriosecond would the chip wake up, from 1 to 65535.
  */
esp_err_t esp_wifi_set_connectionless_wake_interval(uint16_t interval);


**
  * @brief WiFi PHY rate encodings
  *
  */
typedef enum {
    WIFI_PHY_RATE_1M_L      = 0x00, /**< 1 Mbps with long preamble */
    WIFI_PHY_RATE_2M_L      = 0x01, /**< 2 Mbps with long preamble */
    WIFI_PHY_RATE_5M_L      = 0x02, /**< 5.5 Mbps with long preamble */
    WIFI_PHY_RATE_11M_L     = 0x03, /**< 11 Mbps with long preamble */
    WIFI_PHY_RATE_2M_S      = 0x05, /**< 2 Mbps with short preamble */
    WIFI_PHY_RATE_5M_S      = 0x06, /**< 5.5 Mbps with short preamble */
    WIFI_PHY_RATE_11M_S     = 0x07, /**< 11 Mbps with short preamble */
    WIFI_PHY_RATE_48M       = 0x08, /**< 48 Mbps */
    WIFI_PHY_RATE_24M       = 0x09, /**< 24 Mbps */
    WIFI_PHY_RATE_12M       = 0x0A, /**< 12 Mbps */
    WIFI_PHY_RATE_6M        = 0x0B, /**< 6 Mbps */
    WIFI_PHY_RATE_54M       = 0x0C, /**< 54 Mbps */
    WIFI_PHY_RATE_36M       = 0x0D, /**< 36 Mbps */
    WIFI_PHY_RATE_18M       = 0x0E, /**< 18 Mbps */
    WIFI_PHY_RATE_9M        = 0x0F, /**< 9 Mbps */
    WIFI_PHY_RATE_MCS0_LGI  = 0x10, /**< MCS0 with long GI, 6.5 Mbps for 20MHz, 13.5 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS1_LGI  = 0x11, /**< MCS1 with long GI, 13 Mbps for 20MHz, 27 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS2_LGI  = 0x12, /**< MCS2 with long GI, 19.5 Mbps for 20MHz, 40.5 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS3_LGI  = 0x13, /**< MCS3 with long GI, 26 Mbps for 20MHz, 54 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS4_LGI  = 0x14, /**< MCS4 with long GI, 39 Mbps for 20MHz, 81 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS5_LGI  = 0x15, /**< MCS5 with long GI, 52 Mbps for 20MHz, 108 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS6_LGI  = 0x16, /**< MCS6 with long GI, 58.5 Mbps for 20MHz, 121.5 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS7_LGI  = 0x17, /**< MCS7 with long GI, 65 Mbps for 20MHz, 135 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS0_SGI  = 0x18, /**< MCS0 with short GI, 7.2 Mbps for 20MHz, 15 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS1_SGI  = 0x19, /**< MCS1 with short GI, 14.4 Mbps for 20MHz, 30 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS2_SGI  = 0x1A, /**< MCS2 with short GI, 21.7 Mbps for 20MHz, 45 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS3_SGI  = 0x1B, /**< MCS3 with short GI, 28.9 Mbps for 20MHz, 60 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS4_SGI  = 0x1C, /**< MCS4 with short GI, 43.3 Mbps for 20MHz, 90 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS5_SGI  = 0x1D, /**< MCS5 with short GI, 57.8 Mbps for 20MHz, 120 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS6_SGI  = 0x1E, /**< MCS6 with short GI, 65 Mbps for 20MHz, 135 Mbps for 40MHz */
    WIFI_PHY_RATE_MCS7_SGI  = 0x1F, /**< MCS7 with short GI, 72.2 Mbps for 20MHz, 150 Mbps for 40MHz */
    WIFI_PHY_RATE_LORA_250K = 0x29, /**< 250 Kbps */
    WIFI_PHY_RATE_LORA_500K = 0x2A, /**< 500 Kbps */
    WIFI_PHY_RATE_MAX,
} wifi_phy_rate_t;


/** Argument structure for WIFI_EVENT_FTM_REPORT event */
typedef struct {
    uint8_t peer_mac[6];                        /**< MAC address of the FTM Peer */
    wifi_ftm_status_t status;                   /**< Status of the FTM operation */
    uint32_t rtt_raw;                           /**< Raw average Round-Trip-Time with peer in Nano-Seconds */
    uint32_t rtt_est;                           /**< Estimated Round-Trip-Time with peer in Nano-Seconds */
    uint32_t dist_est;                          /**< Estimated one-way distance in Centi-Meters */
    wifi_ftm_report_entry_t *ftm_report_data;   /**< Pointer to FTM Report with multiple entries, should be freed after use */
    uint8_t ftm_report_num_entries;             /**< Number of entries in the FTM Report data */
} wifi_event_ftm_report_t;

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