Add dc_bus_over_power error

Firmware/MotorControl/axis.cpp

@@ -140,6 +140,20 @@ bool Axis::do_checks() {
     if (!(vbus_voltage <= board_config.dc_bus_overvoltage_trip_level))
         error_ |= ERROR_DC_BUS_OVER_VOLTAGE;
 
+    // This is the same math that's used in update_brake_current().  Should we calculate IBus globally?
+    float Ibus_sum = 0.0f;
+    for (size_t i = 0; i < AXIS_COUNT; ++i) {
+        if (axes[i]->motor_.armed_state_ == Motor::ARMED_STATE_ARMED) {
+            Ibus_sum += axes[i]->motor_.current_control_.Ibus;
+        }
+    }
+
+    if(board_config.power_supply_wattage >= 0.0f && 
+            Ibus_sum * vbus_voltage > board_config.power_supply_wattage) 
+    {
+        error_ |= ERROR_DC_BUS_OVER_POWER;
+    }
+
     // Sub-components should use set_error which will propegate to this error_
     motor_.do_checks();
     encoder_.do_checks();

Firmware/MotorControl/axis.hpp

@@ -21,6 +21,7 @@ public:
         ERROR_CONTROLLER_FAILED = 0x200,
         ERROR_POS_CTRL_DURING_SENSORLESS = 0x400,
         ERROR_WATCHDOG_TIMER_EXPIRED = 0x800,
+        ERROR_DC_BUS_OVER_POWER = 0x1000,
     };
 
     enum State_t {

Firmware/MotorControl/odrive_main.h

@@ -81,6 +81,7 @@ struct BoardConfig_t {
                                                                         //<! This protects against cases in which the power supply fails to dissipate
                                                                         //<! the brake power if the brake resistor is disabled.
                                                                         //<! The default is 26V for the 24V board version and 52V for the 48V board version.
+    float power_supply_wattage = 0.0f;
     PWMMapping_t pwm_mappings[GPIO_COUNT];
     PWMMapping_t analog_mappings[GPIO_COUNT];
 };