From eea7758a635f52c5f78f77eded492b1267ec8d5a Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Thu, 1 Dec 2016 20:59:50 +1100
Subject: [PATCH] AP_Baro: added GND_EXT_BUS option

this is needed to enable probing for a MS5611 on external I2C bus. The
MS5611 looks the same as a MS5525 airspeed sensor, so we can't just
auto-probe. Users will need to enable external barometers
---
 libraries/AP_Baro/AP_Baro.cpp        | 18 +++++++++++++-----
 libraries/AP_Baro/AP_Baro.h          |  1 +
 libraries/AP_Baro/AP_Baro_MS5611.cpp |  7 ++++++-
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/libraries/AP_Baro/AP_Baro.cpp b/libraries/AP_Baro/AP_Baro.cpp
index c1f789a732..78f64098a0 100644
--- a/libraries/AP_Baro/AP_Baro.cpp
+++ b/libraries/AP_Baro/AP_Baro.cpp
@@ -78,6 +78,13 @@ const AP_Param::GroupInfo AP_Baro::var_info[] = {
     // @User: Advanced
     AP_GROUPINFO("PRIMARY", 6, AP_Baro, _primary_baro, 0),
 
+    // @Param: EXT_BUS
+    // @DisplayName: External baro bus
+    // @Description: This selects the bus number for looking for an I2C barometer
+    // @Values: -1:Disabled,0:Bus0:1:Bus1
+    // @User: Advanced
+    AP_GROUPINFO("EXT_BUS", 7, AP_Baro, _ext_bus, -1),
+    
     AP_GROUPEND
 };
 
@@ -331,11 +338,6 @@ void AP_Baro::init(void)
                                           std::move(hal.spi->get_device(HAL_BARO_MS5611_SPI_EXT_NAME))));
         ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
                                           std::move(hal.spi->get_device(HAL_BARO_MS5611_NAME))));
-        // can have baro on I2C too
-        ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
-                                          std::move(hal.i2c_mgr->get_device(0, HAL_BARO_MS5611_I2C_ADDR))));
-        ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
-                                          std::move(hal.i2c_mgr->get_device(1, HAL_BARO_MS5611_I2C_ADDR))));
     } else if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXRACER) {
         ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
                                           std::move(hal.spi->get_device(HAL_BARO_MS5611_SPI_INT_NAME))));
@@ -372,6 +374,12 @@ void AP_Baro::init(void)
     _num_drivers = 1;
 #endif
 
+    // can optionally have baro on I2C too
+    if (_ext_bus >= 0) {
+        ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
+                                          std::move(hal.i2c_mgr->get_device(_ext_bus, HAL_BARO_MS5611_I2C_ADDR))));
+    }
+    
     if (_num_drivers == 0 || _num_sensors == 0 || drivers[0] == nullptr) {
         AP_HAL::panic("Baro: unable to initialise driver");
     }
diff --git a/libraries/AP_Baro/AP_Baro.h b/libraries/AP_Baro/AP_Baro.h
index ee51fea1bd..f99e21de93 100644
--- a/libraries/AP_Baro/AP_Baro.h
+++ b/libraries/AP_Baro/AP_Baro.h
@@ -161,6 +161,7 @@ class AP_Baro
     AP_Float                            _alt_offset;
     float                               _alt_offset_active;
     AP_Int8                             _primary_baro; // primary chosen by user
+    AP_Int8                             _ext_bus; // bus number for external barometer
     float                               _last_altitude_EAS2TAS;
     float                               _EAS2TAS;
     float                               _external_temperature;
diff --git a/libraries/AP_Baro/AP_Baro_MS5611.cpp b/libraries/AP_Baro/AP_Baro_MS5611.cpp
index 05d1e22ba3..3e4d235a9c 100644
--- a/libraries/AP_Baro/AP_Baro_MS5611.cpp
+++ b/libraries/AP_Baro/AP_Baro_MS5611.cpp
@@ -90,13 +90,16 @@ bool AP_Baro_MS56XX::_init()
     
     uint16_t prom[8];
     bool prom_read_ok = false;
-    
+
+    const char *name = "MS5611";
     switch (_ms56xx_type) {
     case BARO_MS5607:
+        name = "MS5607";
     case BARO_MS5611:
         prom_read_ok = _read_prom_5611(prom);
         break;
     case BARO_MS5637:
+        name = "MS5637";
         prom_read_ok = _read_prom_5637(prom);
         break;
     }
@@ -106,6 +109,8 @@ bool AP_Baro_MS56XX::_init()
         return false;
     }
 
+    printf("%s found on bus %u address 0x%02x\n", name, _dev->bus_num(), _dev->get_bus_address());
+
     _dev->transfer(&CMD_MS56XX_RESET, 1, nullptr, 0);
     hal.scheduler->delay(4);