AP_Periph: added battery balance plug node

this supports a periph node attached to a LiPo battery balance plug,
reporting via BatteryInfoAux

Tools/AP_Periph/AP_Periph.cpp

@@ -465,6 +465,10 @@ void AP_Periph_FW::update()
     rcin_update();
 #endif
 
+#ifdef HAL_PERIPH_ENABLE_BATTERY_BALANCE
+    batt_balance_update();
+#endif
+    
     static uint32_t fiftyhz_last_update_ms;
     if (now - fiftyhz_last_update_ms >= 20) {
         // update at 50Hz

Tools/AP_Periph/AP_Periph.h

@@ -34,6 +34,7 @@
 #endif
 #include <AP_RCProtocol/AP_RCProtocol_config.h>
 #include "rc_in.h"
+#include "batt_balance.h"
 
 #include <AP_NMEA_Output/AP_NMEA_Output.h>
 #if HAL_NMEA_OUTPUT_ENABLED && !(HAL_GCS_ENABLED && defined(HAL_PERIPH_ENABLE_GPS))
@@ -290,6 +291,11 @@ public:
     Parameters_RCIN g_rcin;
 #endif
 
+#ifdef HAL_PERIPH_ENABLE_BATTERY_BALANCE
+    void batt_balance_update();
+    BattBalance battery_balance;
+#endif
+    
 #if AP_TEMPERATURE_SENSOR_ENABLED
     AP_TemperatureSensor temperature_sensor;
 #endif

Tools/AP_Periph/Parameters.cpp

@@ -569,6 +569,13 @@ const AP_Param::Info AP_Periph_FW::var_info[] = {
     GOBJECT(g_rcin, "RC",  Parameters_RCIN),
 #endif
 
+#ifdef HAL_PERIPH_ENABLE_BATTERY_BALANCE
+    // @Group: BAL
+    // @Path: batt_balance.cpp
+    GOBJECT(battery_balance, "BAL",  BattBalance),
+#endif
+
+    // NOTE: sim parameters should go last
 #if AP_SIM_ENABLED
     // @Group: SIM_
     // @Path: ../libraries/SITL/SITL.cpp

Tools/AP_Periph/Parameters.h

@@ -81,6 +81,7 @@ public:
         k_param_g_rcin,
         k_param_sitl,
         k_param_ahrs,
+        k_param_battery_balance,
     };
 
     AP_Int16 format_version;

Tools/AP_Periph/batt_balance.cpp

@@ -0,0 +1,137 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "AP_Periph.h"
+
+#ifdef HAL_PERIPH_ENABLE_BATTERY_BALANCE
+
+#include <dronecan_msgs.h>
+
+extern const AP_HAL::HAL &hal;
+
+#ifndef AP_PERIPH_BATTERY_BALANCE_NUMCELLS_DEFAULT
+#define AP_PERIPH_BATTERY_BALANCE_NUMCELLS_DEFAULT 0
+#endif
+
+#ifndef AP_PERIPH_BATTERY_BALANCE_RATE_DEFAULT
+#define AP_PERIPH_BATTERY_BALANCE_RATE_DEFAULT 1
+#endif
+
+#ifndef AP_PERIPH_BATTERY_BALANCE_CELL1_PIN_DEFAULT
+#define AP_PERIPH_BATTERY_BALANCE_CELL1_PIN_DEFAULT 1
+#endif
+
+#ifndef AP_PERIPH_BATTERY_BALANCE_ID_DEFAULT
+#define AP_PERIPH_BATTERY_BALANCE_ID_DEFAULT 0
+#endif
+
+
+const AP_Param::GroupInfo BattBalance::var_info[] {
+    // @Param: _NUM_CELLS
+    // @DisplayName: Number of battery cells
+    // @Description: Number of battery cells to monitor
+    // @Range: 0 64
+    AP_GROUPINFO("_NUM_CELLS", 1, BattBalance, num_cells, AP_PERIPH_BATTERY_BALANCE_NUMCELLS_DEFAULT),
+
+    // @Param: _ID
+    // @DisplayName: Battery ID
+    // @Description: Battery ID to match against other batteries
+    // @Range: 0 127
+    AP_GROUPINFO("_ID", 2, BattBalance, id, AP_PERIPH_BATTERY_BALANCE_ID_DEFAULT),
+        
+    // @Param: _RATE
+    // @DisplayName: Send Rate
+    // @Description: Rate to send cell information
+    // @Range: 0 20
+    AP_GROUPINFO("_RATE", 3, BattBalance, rate, AP_PERIPH_BATTERY_BALANCE_RATE_DEFAULT),
+
+    // @Param: _CELL1_PIN
+    // @DisplayName: First analog pin
+    // @Description: Analog pin of the first cell. Later cells must be sequential
+    // @Range: 0 127
+    AP_GROUPINFO("_CELL1_PIN", 4, BattBalance, cell1_pin, AP_PERIPH_BATTERY_BALANCE_CELL1_PIN_DEFAULT),
+        
+    AP_GROUPEND
+};
+
+BattBalance::BattBalance(void)
+{
+    AP_Param::setup_object_defaults(this, var_info);
+}
+
+void AP_Periph_FW::batt_balance_update()
+{
+    const int8_t ncell = battery_balance.num_cells;
+    if (ncell <= 0) {
+        return;
+    }
+
+    // allocate cell sources if needed
+    if (battery_balance.cells == nullptr) {
+        battery_balance.cells = new AP_HAL::AnalogSource*[ncell];
+        if (battery_balance.cells == nullptr) {
+            return;
+        }
+        battery_balance.cells_allocated = ncell;
+        for (uint8_t i=0; i<battery_balance.cells_allocated; i++) {
+            battery_balance.cells[i] = hal.analogin->channel(battery_balance.cell1_pin + i);
+        }
+    }
+
+    const uint32_t now = AP_HAL::millis();
+    if (now - battery_balance.last_send_ms < 1000.0/battery_balance.rate.get()) {
+        return;
+    }
+    battery_balance.last_send_ms = now;
+
+    // allocate space for the packet. This is a large
+    // packet that won't fit on the stack, so dynamically allocate
+    auto *pkt = new ardupilot_equipment_power_BatteryInfoAux;
+    uint8_t *buffer = new uint8_t[ARDUPILOT_EQUIPMENT_POWER_BATTERYINFOAUX_MAX_SIZE];
+    if (pkt == nullptr || buffer == nullptr) {
+        delete pkt;
+        return;
+    }
+
+    pkt->voltage_cell.len = battery_balance.cells_allocated;
+    float last_cell = 0;
+    for (uint8_t i=0; i<battery_balance.cells_allocated; i++) {
+        auto *chan = battery_balance.cells[i];
+        if (chan == nullptr) {
+            continue;
+        }
+        const float v = chan->voltage_average();
+        pkt->voltage_cell.data[i] = v - last_cell;
+        last_cell = v;
+    }
+    pkt->max_current = nanf("");
+    pkt->nominal_voltage = nanf("");
+    pkt->battery_id = uint8_t(battery_balance.id);
+
+    // encode and send message:
+    const uint16_t total_size = ardupilot_equipment_power_BatteryInfoAux_encode(pkt, buffer, !periph.canfdout());
+
+    canard_broadcast(ARDUPILOT_EQUIPMENT_POWER_BATTERYINFOAUX_SIGNATURE,
+                     ARDUPILOT_EQUIPMENT_POWER_BATTERYINFOAUX_ID,
+                     CANARD_TRANSFER_PRIORITY_LOW,
+                     buffer,
+                     total_size);
+
+    delete pkt;
+    delete buffer;
+}
+
+#endif  // HAL_PERIPH_ENABLE_BATTERY_BALANCE
+

Tools/AP_Periph/batt_balance.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#ifdef HAL_PERIPH_ENABLE_BATTERY_BALANCE
+
+class BattBalance {
+public:
+    friend class AP_Periph_FW;
+    BattBalance(void);
+
+    static const struct AP_Param::GroupInfo var_info[];
+
+private:
+    AP_Int8 num_cells;
+    AP_Int8 id;
+    AP_Int8 cell1_pin;
+    AP_Float rate;
+    uint32_t last_send_ms;
+
+    AP_HAL::AnalogSource **cells;
+    uint8_t cells_allocated;
+};
+
+#endif // HAL_PERIPH_ENABLE_BATTERY_BALANCE
+