Merge pull request #915 from wez/ble_3

Add support for Adafruit BLE modules

tmk_core/protocol/lufa/adafruit_ble.cpp

@@ -0,0 +1,805 @@
+#include "adafruit_ble.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <alloca.h>
+#include <util/delay.h>
+#include <util/atomic.h>
+#include "debug.h"
+#include "pincontrol.h"
+#include "timer.h"
+#include "action_util.h"
+#include "ringbuffer.hpp"
+#include <string.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 AdafruitBleResetPin
+#define AdafruitBleResetPin D4
+#endif
+
+#ifndef AdafruitBleCSPin
+#define AdafruitBleCSPin    B4
+#endif
+
+#ifndef AdafruitBleIRQPin
+#define AdafruitBleIRQPin   E6
+#endif
+
+
+#define SAMPLE_BATTERY
+#define ConnectionUpdateInterval 1000 /* milliseconds */
+
+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)) {
+      uint8_t x, y, scroll, pan;
+    } 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,
+};
+
+// The SDEP.md file says 2MHz but the web page and the sample driver
+// both use 4MHz
+#define SpiBusSpeed 4000000
+
+#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);
+
+struct SPI_Settings {
+  uint8_t spcr, spsr;
+};
+
+static struct SPI_Settings spi;
+
+// Initialize 4Mhz MSBFIRST MODE0
+void SPI_init(struct SPI_Settings *spi) {
+  spi->spcr = _BV(SPE) | _BV(MSTR);
+  spi->spsr = _BV(SPI2X);
+
+  static_assert(SpiBusSpeed == F_CPU / 2, "hard coded at 4Mhz");
+
+  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+    // Ensure that SS is OUTPUT High
+    digitalWrite(B0, PinLevelHigh);
+    pinMode(B0, PinDirectionOutput);
+
+    SPCR |= _BV(MSTR);
+    SPCR |= _BV(SPE);
+    pinMode(B1 /* SCK */, PinDirectionOutput);
+    pinMode(B2 /* MOSI */, PinDirectionOutput);
+  }
+}
+
+static inline void SPI_begin(struct SPI_Settings*spi) {
+  SPCR = spi->spcr;
+  SPSR = spi->spsr;
+}
+
+static inline uint8_t SPI_TransferByte(uint8_t data) {
+  SPDR = data;
+  asm volatile("nop");
+  while (!(SPSR & _BV(SPIF))) {
+    ; // wait
+  }
+  return SPDR;
+}
+
+static inline void spi_send_bytes(const uint8_t *buf, uint8_t len) {
+  if (len == 0) return;
+  const uint8_t *end = buf + len;
+  while (buf < end) {
+    SPDR = *buf;
+    while (!(SPSR & _BV(SPIF))) {
+      ; // wait
+    }
+    ++buf;
+  }
+}
+
+static inline uint16_t spi_read_byte(void) {
+  return SPI_TransferByte(0x00 /* dummy */);
+}
+
+static inline void spi_recv_bytes(uint8_t *buf, uint8_t len) {
+  const uint8_t *end = buf + len;
+  if (len == 0) return;
+  while (buf < end) {
+    SPDR = 0; // write a dummy to initiate read
+    while (!(SPSR & _BV(SPIF))) {
+      ; // wait
+    }
+    *buf = SPDR;
+    ++buf;
+  }
+}
+
+#if 0
+static void dump_pkt(const struct sdep_msg *msg) {
+  print("pkt: type=");
+  print_hex8(msg->type);
+  print(" cmd=");
+  print_hex8(msg->cmd_high);
+  print_hex8(msg->cmd_low);
+  print(" len=");
+  print_hex8(msg->len);
+  print(" more=");
+  print_hex8(msg->more);
+  print("\n");
+}
+#endif
+
+// Send a single SDEP packet
+static bool sdep_send_pkt(const struct sdep_msg *msg, uint16_t timeout) {
+  SPI_begin(&spi);
+
+  digitalWrite(AdafruitBleCSPin, PinLevelLow);
+  uint16_t timerStart = timer_read();
+  bool success = false;
+  bool ready = false;
+
+  do {
+    ready = SPI_TransferByte(msg->type) != SdepSlaveNotReady;
+    if (ready) {
+      break;
+    }
+
+    // Release it and let it initialize
+    digitalWrite(AdafruitBleCSPin, PinLevelHigh);
+    _delay_us(SdepBackOff);
+    digitalWrite(AdafruitBleCSPin, PinLevelLow);
+  } while (timer_elapsed(timerStart) < timeout);
+
+  if (ready) {
+    // Slave is ready; send the rest of the packet
+    spi_send_bytes(&msg->cmd_low,
+                   sizeof(*msg) - (1 + sizeof(msg->payload)) + msg->len);
+    success = true;
+  }
+
+  digitalWrite(AdafruitBleCSPin, PinLevelHigh);
+
+  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 = digitalRead(AdafruitBleIRQPin);
+    if (ready) {
+      break;
+    }
+    _delay_us(1);
+  } while (timer_elapsed(timerStart) < timeout);
+
+  if (ready) {
+    SPI_begin(&spi);
+
+    digitalWrite(AdafruitBleCSPin, PinLevelLow);
+
+    do {
+      // Read the command type, waiting for the data to be ready
+      msg->type = spi_read_byte();
+      if (msg->type == SdepSlaveNotReady || msg->type == SdepSlaveOverflow) {
+        // Release it and let it initialize
+        digitalWrite(AdafruitBleCSPin, PinLevelHigh);
+        _delay_us(SdepBackOff);
+        digitalWrite(AdafruitBleCSPin, PinLevelLow);
+        continue;
+      }
+
+      // Read the rest of the header
+      spi_recv_bytes(&msg->cmd_low, sizeof(*msg) - (1 + sizeof(msg->payload)));
+
+      // and get the payload if there is any
+      if (msg->len <= SdepMaxPayload) {
+        spi_recv_bytes(msg->payload, msg->len);
+      }
+      success = true;
+      break;
+    } while (timer_elapsed(timerStart) < timeout);
+
+    digitalWrite(AdafruitBleCSPin, PinLevelHigh);
+  }
+  return success;
+}
+
+static void resp_buf_read_one(bool greedy) {
+  uint16_t last_send;
+  if (!resp_buf.peek(last_send)) {
+    return;
+  }
+
+  if (digitalRead(AdafruitBleIRQPin)) {
+    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) && digitalRead(AdafruitBleIRQPin)) {
+        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");
+    _delay_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;
+
+  pinMode(AdafruitBleIRQPin, PinDirectionInput);
+  pinMode(AdafruitBleCSPin, PinDirectionOutput);
+  digitalWrite(AdafruitBleCSPin, PinLevelHigh);
+
+  SPI_init(&spi);
+
+  // Perform a hardware reset
+  pinMode(AdafruitBleResetPin, PinDirectionOutput);
+  digitalWrite(AdafruitBleResetPin, PinLevelHigh);
+  digitalWrite(AdafruitBleResetPin, PinLevelLow);
+  _delay_ms(10);
+  digitalWrite(AdafruitBleResetPin, PinLevelHigh);
+
+  _delay_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) {
+    auto now = timer_read();
+    while (!resp_buf.enqueue(now)) {
+      resp_buf_read_one(false);
+    }
+    auto 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) {
+  auto cmdbuf = (char *)alloca(strlen_P(cmd) + 1);
+  strcpy_P(cmdbuf, cmd);
+  return at_command(cmdbuf, resp, resplen, verbose);
+}
+
+bool adafruit_ble_is_connected(void) {
+  return state.is_connected;
+}
+
+bool adafruit_ble_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) " " STR(DESCRIPTION);
+  // 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) {
+      print("****** BLE CONNECT!!!!\n");
+    } else {
+      print("****** BLE DISCONNECT!!!!\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 adafruit_ble_task(void) {
+  char resbuf[48];
+
+  if (!state.configured && !adafruit_ble_enable_keyboard()) {
+    return;
+  }
+  resp_buf_read_one(true);
+  send_buf_send_one(SdepShortTimeout);
+
+  if (resp_buf.empty() && (state.event_flags & UsingEvents) &&
+      digitalRead(AdafruitBleIRQPin)) {
+    // 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
+  // I don't know if this really does anything useful yet; the reported
+  // voltage level always seems to be around 3200mV.  We may want to just rip
+  // this code out.
+  if (timer_elapsed(state.last_battery_update) > BatteryUpdateInterval &&
+      resp_buf.empty()) {
+    state.last_battery_update = timer_read();
+
+    if (at_command_P(PSTR("AT+HWVBAT"), resbuf, sizeof(resbuf))) {
+      state.vbat = atoi(resbuf);
+    }
+  }
+#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);
+      return at_command(cmdbuf, NULL, 0, true, timeout);
+#endif
+    default:
+      return true;
+  }
+}
+
+bool adafruit_ble_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 true;
+    }
+
+    nkeys -= 6;
+    keys += 6;
+  }
+
+  return true;
+}
+
+bool adafruit_ble_send_consumer_key(uint16_t keycode, int hold_duration) {
+  struct queue_item item;
+
+  item.queue_type = QTConsumer;
+  item.consumer = keycode;
+
+  while (!send_buf.enqueue(item)) {
+    send_buf_send_one();
+  }
+  return true;
+}
+
+#ifdef MOUSE_ENABLE
+bool adafruit_ble_send_mouse_move(int8_t x, int8_t y, int8_t scroll,
+                                  int8_t pan) {
+  struct queue_item item;
+
+  item.queue_type = QTMouseMove;
+  item.mousemove.x = x;
+  item.mousemove.y = y;
+  item.mousemove.scroll = scroll;
+  item.mousemove.pan = pan;
+
+  while (!send_buf.enqueue(item)) {
+    send_buf_send_one();
+  }
+  return true;
+}
+#endif
+
+uint32_t adafruit_ble_read_battery_voltage(void) {
+  return state.vbat;
+}
+
+bool adafruit_ble_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 adafruit_ble_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);
+}

tmk_core/protocol/lufa/adafruit_ble.h

@@ -0,0 +1,60 @@
+/* Bluetooth Low Energy Protocol for QMK.
+ * Author: Wez Furlong, 2016
+ * Supports the Adafruit BLE board built around the nRF51822 chip.
+ */
+#pragma once
+#ifdef ADAFRUIT_BLE_ENABLE
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Instruct the module to enable HID keyboard support and reset */
+extern bool adafruit_ble_enable_keyboard(void);
+
+/* Query to see if the BLE module is connected */
+extern bool adafruit_ble_query_is_connected(void);
+
+/* Returns true if we believe that the BLE module is connected.
+ * This uses our cached understanding that is maintained by
+ * calling ble_task() periodically. */
+extern bool adafruit_ble_is_connected(void);
+
+/* Call this periodically to process BLE-originated things */
+extern void adafruit_ble_task(void);
+
+/* Generates keypress events for a set of keys.
+ * The hid modifier mask specifies the state of the modifier keys for
+ * this set of keys.
+ * Also sends a key release indicator, so that the keys do not remain
+ * held down. */
+extern bool adafruit_ble_send_keys(uint8_t hid_modifier_mask, uint8_t *keys,
+                                   uint8_t nkeys);
+
+/* Send a consumer keycode, holding it down for the specified duration
+ * (milliseconds) */
+extern bool adafruit_ble_send_consumer_key(uint16_t keycode, int hold_duration);
+
+#ifdef MOUSE_ENABLE
+/* Send a mouse/wheel movement report.
+ * The parameters are signed and indicate positive of negative direction
+ * change. */
+extern bool adafruit_ble_send_mouse_move(int8_t x, int8_t y, int8_t scroll,
+                                         int8_t pan);
+#endif
+
+/* Compute battery voltage by reading an analog pin.
+ * Returns the integer number of millivolts */
+extern uint32_t adafruit_ble_read_battery_voltage(void);
+
+extern bool adafruit_ble_set_mode_leds(bool on);
+extern bool adafruit_ble_set_power_level(int8_t level);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // ADAFRUIT_BLE_ENABLE

tmk_core/protocol/lufa/ringbuffer.hpp

@@ -0,0 +1,66 @@
+#pragma once
+// A simple ringbuffer holding Size elements of type T
+template <typename T, uint8_t Size>
+class RingBuffer {
+ protected:
+  T buf_[Size];
+  uint8_t head_{0}, tail_{0};
+ public:
+  inline uint8_t nextPosition(uint8_t position) {
+    return (position + 1) % Size;
+  }
+
+  inline uint8_t prevPosition(uint8_t position) {
+    if (position == 0) {
+      return Size - 1;
+    }
+    return position - 1;
+  }
+
+  inline bool enqueue(const T &item) {
+    static_assert(Size > 1, "RingBuffer size must be > 1");
+    uint8_t next = nextPosition(head_);
+    if (next == tail_) {
+      // Full
+      return false;
+    }
+
+    buf_[head_] = item;
+    head_ = next;
+    return true;
+  }
+
+  inline bool get(T &dest, bool commit = true) {
+    auto tail = tail_;
+    if (tail == head_) {
+      // No more data
+      return false;
+    }
+
+    dest = buf_[tail];
+    tail = nextPosition(tail);
+
+    if (commit) {
+      tail_ = tail;
+    }
+    return true;
+  }
+
+  inline bool empty() const { return head_ == tail_; }
+
+  inline uint8_t size() const {
+    int diff = head_ - tail_;
+    if (diff >= 0) {
+      return diff;
+    }
+    return Size + diff;
+  }
+
+  inline T& front() {
+    return buf_[tail_];
+  }
+
+  inline bool peek(T &item) {
+    return get(item, false);
+  }
+};