Merge pull request #24 from nvlsianpu/nrf5x_lf_clk_config

NRF5x LF clk config over mbed config system

hal/targets.json

@@ -1107,7 +1107,13 @@
         },
         "program_cycle_s": 6,
         "default_build": "small",
-        "features": ["BLE"]
+        "features": ["BLE"],
+        "config":{
+            "lf_clock_src": {
+                "value": "NRF_LF_SRC_XTAL",
+                "macro_name": "MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC"
+            }
+        }
     },
     "MCU_NRF51_16K_BASE": {
         "inherits": ["MCU_NRF51"],
@@ -1721,7 +1727,13 @@
             "toolchains": ["ARM_STD", "GCC_ARM", "IAR"]
         },
         "MERGE_BOOTLOADER": false,
-        "features": ["BLE"]
+        "features": ["BLE"],
+        "config":{
+            "lf_clock_src": {
+                "value": "NRF_LF_SRC_XTAL",
+                "macro_name": "MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC"
+            }
+        }
     },
     "NRF52_DK": {
         "supported_form_factors": ["ARDUINO"],

hal/targets/cmsis/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF51822/system_nrf51.c

@@ -44,6 +44,7 @@
 #include <stdbool.h>
 #include "nrf.h"
 #include "system_nrf51.h"
+#include "nrf5x_lf_clk_helper.h"
 
 /*lint ++flb "Enter library region" */
 
@@ -103,9 +104,9 @@ void SystemInit(void)
         }
         *(uint32_t volatile *)0x4006EC14 = 0xC0;
     }
-
-    // Start the external 32khz crystal oscillator.
-    NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
+    
+    // Start the LF oscilator according to the mbed configuration (over the nrf5x_lf_clk_helper.h file)
+    NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_TO_USE << CLOCK_LFCLKSRC_SRC_Pos);
     NRF_CLOCK->EVENTS_LFCLKSTARTED  = 0;
     NRF_CLOCK->TASKS_LFCLKSTART     = 1;
 

hal/targets/cmsis/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/system_nrf52.c

@@ -41,6 +41,7 @@
 #include <stdbool.h>
 #include "nrf.h"
 #include "system_nrf52.h"
+#include "nrf5x_lf_clk_helper.h"
 
 /*lint ++flb "Enter library region" */
 
@@ -197,8 +198,8 @@ void SystemInit(void)
 
     SystemCoreClockUpdate();
 
-    // Start the external 32khz crystal oscillator.
-    NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
+    // Start the LF oscilator according to the mbed configuration (over the nrf5x_lf_clk_helper.h file)
+    NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_TO_USE << CLOCK_LFCLKSRC_SRC_Pos);
     NRF_CLOCK->EVENTS_LFCLKSTARTED  = 0;
     NRF_CLOCK->TASKS_LFCLKSTART     = 1;
 

hal/targets/cmsis/TARGET_NORDIC/TARGET_NRF5/nrf5x_lf_clk_helper.h

@@ -0,0 +1,66 @@
+/* 
+ * Copyright (c) 2016 Nordic Semiconductor ASA
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ * 
+ *   1. Redistributions of source code must retain the above copyright notice, this list 
+ *      of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form, except as embedded into a Nordic Semiconductor ASA 
+ *      integrated circuit in a product or a software update for such product, must reproduce 
+ *      the above copyright notice, this list of conditions and the following disclaimer in 
+ *      the documentation and/or other materials provided with the distribution.
+ *
+ *   3. Neither the name of Nordic Semiconductor ASA nor the names of its contributors may be 
+ *      used to endorse or promote products derived from this software without specific prior 
+ *      written permission.
+ *
+ *   4. This software, with or without modification, must only be used with a 
+ *      Nordic Semiconductor ASA integrated circuit.
+ *
+ *   5. Any software provided in binary or object form under this license must not be reverse 
+ *      engineered, decompiled, modified and/or disassembled. 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ */
+
+#ifndef __NRF5X_LF_CLK_HELPER_H_
+    
+#ifndef MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC
+    #define MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC (NRF_LF_SRC_XTAL)
+    #warning No configuration for LF clock source. Xtal source will be used as a default configuration.
+#endif
+
+
+
+#define NRF_LF_SRC_XTAL  2 
+#define NRF_LF_SRC_SYNTH 3 
+#define NRF_LF_SRC_RC    4
+
+#if MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC == NRF_LF_SRC_SYNTH
+    #define CLOCK_LFCLKSRC_SRC_TO_USE (CLOCK_LFCLKSRC_SRC_Synth)
+#elif MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC == NRF_LF_SRC_XTAL
+    #define CLOCK_LFCLKSRC_SRC_TO_USE (CLOCK_LFCLKSRC_SRC_Xtal)
+#elif MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC == NRF_LF_SRC_RC
+    #define CLOCK_LFCLKSRC_SRC_TO_USE (CLOCK_LFCLKSRC_SRC_RC)
+#else
+    #error Bad LFCLK configuration. Declare proper source through mbed configuration.
+#endif
+
+#undef NRF_LF_SRC_XTAL
+#undef NRF_LF_SRC_SYNTH
+#undef NRF_LF_SRC_RC
+
+#endif