Rename `AdafruitBLE` to `BluefruitLE` (#16127)

1 files changed, 699 insertions, 0 deletions

diff --git a/drivers/bluetooth/bluefruit_le.cpp b/drivers/bluetooth/bluefruit_le.cpp
new file mode 100644
index 0000000000..86581a1a48
--- /dev/null
+++ b/drivers/bluetooth/bluefruit_le.cpp
@@ -0,0 +1,699 @@
+#include "bluefruit_le.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <alloca.h>
+#include "debug.h"
+#include "timer.h"
+#include "action_util.h"
+#include "ringbuffer.hpp"
+#include <string.h>
+#include "spi_master.h"
+#include "wait.h"
+#include "analog.h"
+#include "progmem.h"
+
+// These are the pin assignments for the 32u4 boards.
+// You may define them to something else in your config.h
+// if yours is wired up differently.
+#ifndef BLUEFRUIT_LE_RST_PIN
+#    define BLUEFRUIT_LE_RST_PIN D4
+#endif
+
+#ifndef BLUEFRUIT_LE_CS_PIN
+#    define BLUEFRUIT_LE_CS_PIN B4
+#endif
+
+#ifndef BLUEFRUIT_LE_IRQ_PIN
+#    define BLUEFRUIT_LE_IRQ_PIN E6
+#endif
+
+#ifndef BLUEFRUIT_LE_SCK_DIVISOR
+#    define BLUEFRUIT_LE_SCK_DIVISOR 2  // 4MHz SCK/8MHz CPU, calculated for Feather 32U4 BLE
+#endif
+
+#define SAMPLE_BATTERY
+#define ConnectionUpdateInterval 1000 /* milliseconds */
+
+#ifndef BATTERY_LEVEL_PIN
+#    define BATTERY_LEVEL_PIN B5
+#endif
+
+static struct {
+    bool is_connected;
+    bool initialized;
+    bool configured;
+
+#define ProbedEvents 1
+#define UsingEvents 2
+    bool event_flags;
+
+#ifdef SAMPLE_BATTERY
+    uint16_t last_battery_update;
+    uint32_t vbat;
+#endif
+    uint16_t last_connection_update;
+} state;
+
+// Commands are encoded using SDEP and sent via SPI
+// https://github.com/adafruit/Adafruit_BluefruitLE_nRF51/blob/master/SDEP.md
+
+#define SdepMaxPayload 16
+struct sdep_msg {
+    uint8_t type;
+    uint8_t cmd_low;
+    uint8_t cmd_high;
+    struct __attribute__((packed)) {
+        uint8_t len : 7;
+        uint8_t more : 1;
+    };
+    uint8_t payload[SdepMaxPayload];
+} __attribute__((packed));
+
+// The recv latency is relatively high, so when we're hammering keys quickly,
+// we want to avoid waiting for the responses in the matrix loop.  We maintain
+// a short queue for that.  Since there is quite a lot of space overhead for
+// the AT command representation wrapped up in SDEP, we queue the minimal
+// information here.
+
+enum queue_type {
+    QTKeyReport,  // 1-byte modifier + 6-byte key report
+    QTConsumer,   // 16-bit key code
+#ifdef MOUSE_ENABLE
+    QTMouseMove,  // 4-byte mouse report
+#endif
+};
+
+struct queue_item {
+    enum queue_type queue_type;
+    uint16_t        added;
+    union __attribute__((packed)) {
+        struct __attribute__((packed)) {
+            uint8_t modifier;
+            uint8_t keys[6];
+        } key;
+
+        uint16_t consumer;
+        struct __attribute__((packed)) {
+            int8_t  x, y, scroll, pan;
+            uint8_t buttons;
+        } mousemove;
+    };
+};
+
+// Items that we wish to send
+static RingBuffer<queue_item, 40> send_buf;
+// Pending response; while pending, we can't send any more requests.
+// This records the time at which we sent the command for which we
+// are expecting a response.
+static RingBuffer<uint16_t, 2> resp_buf;
+
+static bool process_queue_item(struct queue_item *item, uint16_t timeout);
+
+enum sdep_type {
+    SdepCommand       = 0x10,
+    SdepResponse      = 0x20,
+    SdepAlert         = 0x40,
+    SdepError         = 0x80,
+    SdepSlaveNotReady = 0xFE,  // Try again later
+    SdepSlaveOverflow = 0xFF,  // You read more data than is available
+};
+
+enum ble_cmd {
+    BleInitialize = 0xBEEF,
+    BleAtWrapper  = 0x0A00,
+    BleUartTx     = 0x0A01,
+    BleUartRx     = 0x0A02,
+};
+
+enum ble_system_event_bits {
+    BleSystemConnected    = 0,
+    BleSystemDisconnected = 1,
+    BleSystemUartRx       = 8,
+    BleSystemMidiRx       = 10,
+};
+
+#define SdepTimeout 150             /* milliseconds */
+#define SdepShortTimeout 10         /* milliseconds */
+#define SdepBackOff 25              /* microseconds */
+#define BatteryUpdateInterval 10000 /* milliseconds */
+
+static bool at_command(const char *cmd, char *resp, uint16_t resplen, bool verbose, uint16_t timeout = SdepTimeout);
+static bool at_command_P(const char *cmd, char *resp, uint16_t resplen, bool verbose = false);
+
+// Send a single SDEP packet
+static bool sdep_send_pkt(const struct sdep_msg *msg, uint16_t timeout) {
+    spi_start(BLUEFRUIT_LE_CS_PIN, false, 0, BLUEFRUIT_LE_SCK_DIVISOR);
+    uint16_t timerStart = timer_read();
+    bool     success    = false;
+    bool     ready      = false;
+
+    do {
+        ready = spi_write(msg->type) != SdepSlaveNotReady;
+        if (ready) {
+            break;
+        }
+
+        // Release it and let it initialize
+        spi_stop();
+        wait_us(SdepBackOff);
+        spi_start(BLUEFRUIT_LE_CS_PIN, false, 0, BLUEFRUIT_LE_SCK_DIVISOR);
+    } while (timer_elapsed(timerStart) < timeout);
+
+    if (ready) {
+        // Slave is ready; send the rest of the packet
+        spi_transmit(&msg->cmd_low, sizeof(*msg) - (1 + sizeof(msg->payload)) + msg->len);
+        success = true;
+    }
+
+    spi_stop();
+
+    return success;
+}
+
+static inline void sdep_build_pkt(struct sdep_msg *msg, uint16_t command, const uint8_t *payload, uint8_t len, bool moredata) {
+    msg->type     = SdepCommand;
+    msg->cmd_low  = command & 0xFF;
+    msg->cmd_high = command >> 8;
+    msg->len      = len;
+    msg->more     = (moredata && len == SdepMaxPayload) ? 1 : 0;
+
+    static_assert(sizeof(*msg) == 20, "msg is correctly packed");
+
+    memcpy(msg->payload, payload, len);
+}
+
+// Read a single SDEP packet
+static bool sdep_recv_pkt(struct sdep_msg *msg, uint16_t timeout) {
+    bool     success    = false;
+    uint16_t timerStart = timer_read();
+    bool     ready      = false;
+
+    do {
+        ready = readPin(BLUEFRUIT_LE_IRQ_PIN);
+        if (ready) {
+            break;
+        }
+        wait_us(1);
+    } while (timer_elapsed(timerStart) < timeout);
+
+    if (ready) {
+        spi_start(BLUEFRUIT_LE_CS_PIN, false, 0, BLUEFRUIT_LE_SCK_DIVISOR);
+
+        do {
+            // Read the command type, waiting for the data to be ready
+            msg->type = spi_read();
+            if (msg->type == SdepSlaveNotReady || msg->type == SdepSlaveOverflow) {
+                // Release it and let it initialize
+                spi_stop();
+                wait_us(SdepBackOff);
+                spi_start(BLUEFRUIT_LE_CS_PIN, false, 0, BLUEFRUIT_LE_SCK_DIVISOR);
+                continue;
+            }
+
+            // Read the rest of the header
+            spi_receive(&msg->cmd_low, sizeof(*msg) - (1 + sizeof(msg->payload)));
+
+            // and get the payload if there is any
+            if (msg->len <= SdepMaxPayload) {
+                spi_receive(msg->payload, msg->len);
+            }
+            success = true;
+            break;
+        } while (timer_elapsed(timerStart) < timeout);
+
+        spi_stop();
+    }
+    return success;
+}
+
+static void resp_buf_read_one(bool greedy) {
+    uint16_t last_send;
+    if (!resp_buf.peek(last_send)) {
+        return;
+    }
+
+    if (readPin(BLUEFRUIT_LE_IRQ_PIN)) {
+        struct sdep_msg msg;
+
+    again:
+        if (sdep_recv_pkt(&msg, SdepTimeout)) {
+            if (!msg.more) {
+                // We got it; consume this entry
+                resp_buf.get(last_send);
+                dprintf("recv latency %dms\n", TIMER_DIFF_16(timer_read(), last_send));
+            }
+
+            if (greedy && resp_buf.peek(last_send) && readPin(BLUEFRUIT_LE_IRQ_PIN)) {
+                goto again;
+            }
+        }
+
+    } else if (timer_elapsed(last_send) > SdepTimeout * 2) {
+        dprintf("waiting_for_result: timeout, resp_buf size %d\n", (int)resp_buf.size());
+
+        // Timed out: consume this entry
+        resp_buf.get(last_send);
+    }
+}
+
+static void send_buf_send_one(uint16_t timeout = SdepTimeout) {
+    struct queue_item item;
+
+    // Don't send anything more until we get an ACK
+    if (!resp_buf.empty()) {
+        return;
+    }
+
+    if (!send_buf.peek(item)) {
+        return;
+    }
+    if (process_queue_item(&item, timeout)) {
+        // commit that peek
+        send_buf.get(item);
+        dprintf("send_buf_send_one: have %d remaining\n", (int)send_buf.size());
+    } else {
+        dprint("failed to send, will retry\n");
+        wait_ms(SdepTimeout);
+        resp_buf_read_one(true);
+    }
+}
+
+static void resp_buf_wait(const char *cmd) {
+    bool didPrint = false;
+    while (!resp_buf.empty()) {
+        if (!didPrint) {
+            dprintf("wait on buf for %s\n", cmd);
+            didPrint = true;
+        }
+        resp_buf_read_one(true);
+    }
+}
+
+static bool ble_init(void) {
+    state.initialized  = false;
+    state.configured   = false;
+    state.is_connected = false;
+
+    setPinInput(BLUEFRUIT_LE_IRQ_PIN);
+
+    spi_init();
+
+    // Perform a hardware reset
+    setPinOutput(BLUEFRUIT_LE_RST_PIN);
+    writePinHigh(BLUEFRUIT_LE_RST_PIN);
+    writePinLow(BLUEFRUIT_LE_RST_PIN);
+    wait_ms(10);
+    writePinHigh(BLUEFRUIT_LE_RST_PIN);
+
+    wait_ms(1000);  // Give it a second to initialize
+
+    state.initialized = true;
+    return state.initialized;
+}
+
+static inline uint8_t min(uint8_t a, uint8_t b) { return a < b ? a : b; }
+
+static bool read_response(char *resp, uint16_t resplen, bool verbose) {
+    char *dest = resp;
+    char *end  = dest + resplen;
+
+    while (true) {
+        struct sdep_msg msg;
+
+        if (!sdep_recv_pkt(&msg, 2 * SdepTimeout)) {
+            dprint("sdep_recv_pkt failed\n");
+            return false;
+        }
+
+        if (msg.type != SdepResponse) {
+            *resp = 0;
+            return false;
+        }
+
+        uint8_t len = min(msg.len, end - dest);
+        if (len > 0) {
+            memcpy(dest, msg.payload, len);
+            dest += len;
+        }
+
+        if (!msg.more) {
+            // No more data is expected!
+            break;
+        }
+    }
+
+    // Ensure the response is NUL terminated
+    *dest = 0;
+
+    // "Parse" the result text; we want to snip off the trailing OK or ERROR line
+    // Rewind past the possible trailing CRLF so that we can strip it
+    --dest;
+    while (dest > resp && (dest[0] == '\n' || dest[0] == '\r')) {
+        *dest = 0;
+        --dest;
+    }
+
+    // Look back for start of preceeding line
+    char *last_line = strrchr(resp, '\n');
+    if (last_line) {
+        ++last_line;
+    } else {
+        last_line = resp;
+    }
+
+    bool              success       = false;
+    static const char kOK[] PROGMEM = "OK";
+
+    success = !strcmp_P(last_line, kOK);
+
+    if (verbose || !success) {
+        dprintf("result: %s\n", resp);
+    }
+    return success;
+}
+
+static bool at_command(const char *cmd, char *resp, uint16_t resplen, bool verbose, uint16_t timeout) {
+    const char *    end = cmd + strlen(cmd);
+    struct sdep_msg msg;
+
+    if (verbose) {
+        dprintf("ble send: %s\n", cmd);
+    }
+
+    if (resp) {
+        // They want to decode the response, so we need to flush and wait
+        // for all pending I/O to finish before we start this one, so
+        // that we don't confuse the results
+        resp_buf_wait(cmd);
+        *resp = 0;
+    }
+
+    // Fragment the command into a series of SDEP packets
+    while (end - cmd > SdepMaxPayload) {
+        sdep_build_pkt(&msg, BleAtWrapper, (uint8_t *)cmd, SdepMaxPayload, true);
+        if (!sdep_send_pkt(&msg, timeout)) {
+            return false;
+        }
+        cmd += SdepMaxPayload;
+    }
+
+    sdep_build_pkt(&msg, BleAtWrapper, (uint8_t *)cmd, end - cmd, false);
+    if (!sdep_send_pkt(&msg, timeout)) {
+        return false;
+    }
+
+    if (resp == NULL) {
+        uint16_t now = timer_read();
+        while (!resp_buf.enqueue(now)) {
+            resp_buf_read_one(false);
+        }
+        uint16_t later = timer_read();
+        if (TIMER_DIFF_16(later, now) > 0) {
+            dprintf("waited %dms for resp_buf\n", TIMER_DIFF_16(later, now));
+        }
+        return true;
+    }
+
+    return read_response(resp, resplen, verbose);
+}
+
+bool at_command_P(const char *cmd, char *resp, uint16_t resplen, bool verbose) {
+    char *cmdbuf = (char *)alloca(strlen_P(cmd) + 1);
+    strcpy_P(cmdbuf, cmd);
+    return at_command(cmdbuf, resp, resplen, verbose);
+}
+
+bool bluefruit_le_is_connected(void) { return state.is_connected; }
+
+bool bluefruit_le_enable_keyboard(void) {
+    char resbuf[128];
+
+    if (!state.initialized && !ble_init()) {
+        return false;
+    }
+
+    state.configured = false;
+
+    // Disable command echo
+    static const char kEcho[] PROGMEM = "ATE=0";
+    // Make the advertised name match the keyboard
+    static const char kGapDevName[] PROGMEM = "AT+GAPDEVNAME=" STR(PRODUCT);
+    // Turn on keyboard support
+    static const char kHidEnOn[] PROGMEM = "AT+BLEHIDEN=1";
+
+    // Adjust intervals to improve latency.  This causes the "central"
+    // system (computer/tablet) to poll us every 10-30 ms.  We can't
+    // set a smaller value than 10ms, and 30ms seems to be the natural
+    // processing time on my macbook.  Keeping it constrained to that
+    // feels reasonable to type to.
+    static const char kGapIntervals[] PROGMEM = "AT+GAPINTERVALS=10,30,,";
+
+    // Reset the device so that it picks up the above changes
+    static const char kATZ[] PROGMEM = "ATZ";
+
+    // Turn down the power level a bit
+    static const char  kPower[] PROGMEM             = "AT+BLEPOWERLEVEL=-12";
+    static PGM_P const configure_commands[] PROGMEM = {
+        kEcho, kGapIntervals, kGapDevName, kHidEnOn, kPower, kATZ,
+    };
+
+    uint8_t i;
+    for (i = 0; i < sizeof(configure_commands) / sizeof(configure_commands[0]); ++i) {
+        PGM_P cmd;
+        memcpy_P(&cmd, configure_commands + i, sizeof(cmd));
+
+        if (!at_command_P(cmd, resbuf, sizeof(resbuf))) {
+            dprintf("failed BLE command: %S: %s\n", cmd, resbuf);
+            goto fail;
+        }
+    }
+
+    state.configured = true;
+
+    // Check connection status in a little while; allow the ATZ time
+    // to kick in.
+    state.last_connection_update = timer_read();
+fail:
+    return state.configured;
+}
+
+static void set_connected(bool connected) {
+    if (connected != state.is_connected) {
+        if (connected) {
+            dprint("BLE connected\n");
+        } else {
+            dprint("BLE disconnected\n");
+        }
+        state.is_connected = connected;
+
+        // TODO: if modifiers are down on the USB interface and
+        // we cut over to BLE or vice versa, they will remain stuck.
+        // This feels like a good point to do something like clearing
+        // the keyboard and/or generating a fake all keys up message.
+        // However, I've noticed that it takes a couple of seconds
+        // for macOS to to start recognizing key presses after BLE
+        // is in the connected state, so I worry that doing that
+        // here may not be good enough.
+    }
+}
+
+void bluefruit_le_task(void) {
+    char resbuf[48];
+
+    if (!state.configured && !bluefruit_le_enable_keyboard()) {
+        return;
+    }
+    resp_buf_read_one(true);
+    send_buf_send_one(SdepShortTimeout);
+
+    if (resp_buf.empty() && (state.event_flags & UsingEvents) && readPin(BLUEFRUIT_LE_IRQ_PIN)) {
+        // Must be an event update
+        if (at_command_P(PSTR("AT+EVENTSTATUS"), resbuf, sizeof(resbuf))) {
+            uint32_t mask = strtoul(resbuf, NULL, 16);
+
+            if (mask & BleSystemConnected) {
+                set_connected(true);
+            } else if (mask & BleSystemDisconnected) {
+                set_connected(false);
+            }
+        }
+    }
+
+    if (timer_elapsed(state.last_connection_update) > ConnectionUpdateInterval) {
+        bool shouldPoll = true;
+        if (!(state.event_flags & ProbedEvents)) {
+            // Request notifications about connection status changes.
+            // This only works in SPIFRIEND firmware > 0.6.7, which is why
+            // we check for this conditionally here.
+            // Note that at the time of writing, HID reports only work correctly
+            // with Apple products on firmware version 0.6.7!
+            // https://forums.adafruit.com/viewtopic.php?f=8&t=104052
+            if (at_command_P(PSTR("AT+EVENTENABLE=0x1"), resbuf, sizeof(resbuf))) {
+                at_command_P(PSTR("AT+EVENTENABLE=0x2"), resbuf, sizeof(resbuf));
+                state.event_flags |= UsingEvents;
+            }
+            state.event_flags |= ProbedEvents;
+
+            // leave shouldPoll == true so that we check at least once
+            // before relying solely on events
+        } else {
+            shouldPoll = false;
+        }
+
+        static const char kGetConn[] PROGMEM = "AT+GAPGETCONN";
+        state.last_connection_update         = timer_read();
+
+        if (at_command_P(kGetConn, resbuf, sizeof(resbuf))) {
+            set_connected(atoi(resbuf));
+        }
+    }
+
+#ifdef SAMPLE_BATTERY
+    if (timer_elapsed(state.last_battery_update) > BatteryUpdateInterval && resp_buf.empty()) {
+        state.last_battery_update = timer_read();
+
+        state.vbat = analogReadPin(BATTERY_LEVEL_PIN);
+    }
+#endif
+}
+
+static bool process_queue_item(struct queue_item *item, uint16_t timeout) {
+    char cmdbuf[48];
+    char fmtbuf[64];
+
+    // Arrange to re-check connection after keys have settled
+    state.last_connection_update = timer_read();
+
+#if 1
+    if (TIMER_DIFF_16(state.last_connection_update, item->added) > 0) {
+        dprintf("send latency %dms\n", TIMER_DIFF_16(state.last_connection_update, item->added));
+    }
+#endif
+
+    switch (item->queue_type) {
+        case QTKeyReport:
+            strcpy_P(fmtbuf, PSTR("AT+BLEKEYBOARDCODE=%02x-00-%02x-%02x-%02x-%02x-%02x-%02x"));
+            snprintf(cmdbuf, sizeof(cmdbuf), fmtbuf, item->key.modifier, item->key.keys[0], item->key.keys[1], item->key.keys[2], item->key.keys[3], item->key.keys[4], item->key.keys[5]);
+            return at_command(cmdbuf, NULL, 0, true, timeout);
+
+        case QTConsumer:
+            strcpy_P(fmtbuf, PSTR("AT+BLEHIDCONTROLKEY=0x%04x"));
+            snprintf(cmdbuf, sizeof(cmdbuf), fmtbuf, item->consumer);
+            return at_command(cmdbuf, NULL, 0, true, timeout);
+
+#ifdef MOUSE_ENABLE
+        case QTMouseMove:
+            strcpy_P(fmtbuf, PSTR("AT+BLEHIDMOUSEMOVE=%d,%d,%d,%d"));
+            snprintf(cmdbuf, sizeof(cmdbuf), fmtbuf, item->mousemove.x, item->mousemove.y, item->mousemove.scroll, item->mousemove.pan);
+            if (!at_command(cmdbuf, NULL, 0, true, timeout)) {
+                return false;
+            }
+            strcpy_P(cmdbuf, PSTR("AT+BLEHIDMOUSEBUTTON="));
+            if (item->mousemove.buttons & MOUSE_BTN1) {
+                strcat(cmdbuf, "L");
+            }
+            if (item->mousemove.buttons & MOUSE_BTN2) {
+                strcat(cmdbuf, "R");
+            }
+            if (item->mousemove.buttons & MOUSE_BTN3) {
+                strcat(cmdbuf, "M");
+            }
+            if (item->mousemove.buttons == 0) {
+                strcat(cmdbuf, "0");
+            }
+            return at_command(cmdbuf, NULL, 0, true, timeout);
+#endif
+        default:
+            return true;
+    }
+}
+
+void bluefruit_le_send_keys(uint8_t hid_modifier_mask, uint8_t *keys, uint8_t nkeys) {
+    struct queue_item item;
+    bool              didWait = false;
+
+    item.queue_type   = QTKeyReport;
+    item.key.modifier = hid_modifier_mask;
+    item.added        = timer_read();
+
+    while (nkeys >= 0) {
+        item.key.keys[0] = keys[0];
+        item.key.keys[1] = nkeys >= 1 ? keys[1] : 0;
+        item.key.keys[2] = nkeys >= 2 ? keys[2] : 0;
+        item.key.keys[3] = nkeys >= 3 ? keys[3] : 0;
+        item.key.keys[4] = nkeys >= 4 ? keys[4] : 0;
+        item.key.keys[5] = nkeys >= 5 ? keys[5] : 0;
+
+        if (!send_buf.enqueue(item)) {
+            if (!didWait) {
+                dprint("wait for buf space\n");
+                didWait = true;
+            }
+            send_buf_send_one();
+            continue;
+        }
+
+        if (nkeys <= 6) {
+            return;
+        }
+
+        nkeys -= 6;
+        keys += 6;
+    }
+}
+
+void bluefruit_le_send_consumer_key(uint16_t usage) {
+    struct queue_item item;
+
+    item.queue_type = QTConsumer;
+    item.consumer   = usage;
+
+    while (!send_buf.enqueue(item)) {
+        send_buf_send_one();
+    }
+}
+
+#ifdef MOUSE_ENABLE
+void bluefruit_le_send_mouse_move(int8_t x, int8_t y, int8_t scroll, int8_t pan, uint8_t buttons) {
+    struct queue_item item;
+
+    item.queue_type        = QTMouseMove;
+    item.mousemove.x       = x;
+    item.mousemove.y       = y;
+    item.mousemove.scroll  = scroll;
+    item.mousemove.pan     = pan;
+    item.mousemove.buttons = buttons;
+
+    while (!send_buf.enqueue(item)) {
+        send_buf_send_one();
+    }
+}
+#endif
+
+uint32_t bluefruit_le_read_battery_voltage(void) { return state.vbat; }
+
+bool bluefruit_le_set_mode_leds(bool on) {
+    if (!state.configured) {
+        return false;
+    }
+
+    // The "mode" led is the red blinky one
+    at_command_P(on ? PSTR("AT+HWMODELED=1") : PSTR("AT+HWMODELED=0"), NULL, 0);
+
+    // Pin 19 is the blue "connected" LED; turn that off too.
+    // When turning LEDs back on, don't turn that LED on if we're
+    // not connected, as that would be confusing.
+    at_command_P(on && state.is_connected ? PSTR("AT+HWGPIO=19,1") : PSTR("AT+HWGPIO=19,0"), NULL, 0);
+    return true;
+}
+
+// https://learn.adafruit.com/adafruit-feather-32u4-bluefruit-le/ble-generic#at-plus-blepowerlevel
+bool bluefruit_le_set_power_level(int8_t level) {
+    char cmd[46];
+    if (!state.configured) {
+        return false;
+    }
+    snprintf(cmd, sizeof(cmd), "AT+BLEPOWERLEVEL=%d", level);
+    return at_command(cmd, NULL, 0, false);
+}