stmhal: For LIMIFROG board, add early-init function to get to DFU mode.

stmhal/boards/LIMIFROG/board_init.c

@@ -0,0 +1,154 @@
+// The code is this file allows the user to enter DFU mode when the board
+// starts up, by connecting POS10 on the external connector to GND.
+// The code itself is taken from the LimiFrog software repository found at
+// https://github.com/LimiFrog/LimiFrog-SW, and the original license header
+// is copied below.
+
+#include STM32_HAL_H
+
+static void LBF_DFU_If_Needed(void);
+
+void LIMIFROG_board_early_init(void) {
+    LBF_DFU_If_Needed();
+}
+
+/*******************************************************************************
+ * LBF_DFU_If_Needed.c
+ *
+ * (c)2015 LimiFrog / CYMEYA
+ * This program is licensed under the terms of the MIT License.
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND.
+ * Please refer to the License File LICENSE.txt located at the root of this
+ * project for full licensing conditions,
+ * or visit https://opensource.org/licenses/MIT.
+ ******************************************************************************/
+
+#define __LIMIFROG_02
+
+/*  ==== BTLE (excl UART)       ======================================== */
+// PC9 = BT_RST (active high)
+
+#define BT_RST_PIN  GPIO_PIN_9
+#define BT_RST_PORT GPIOC
+
+// Position 10
+#ifdef __LIMIFROG_01
+  #define   CONN_POS10_PIN      GPIO_PIN_9
+  #define   CONN_POS10_PORT     GPIOB
+#else
+  #define   CONN_POS10_PIN      GPIO_PIN_8
+  #define   CONN_POS10_PORT     GPIOB
+#endif
+
+static inline void  GPIO_HIGH(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)
+{
+       GPIOx->BSRR = (uint32_t)GPIO_Pin;
+}
+
+static inline int  IS_GPIO_RESET(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)
+{
+    GPIO_PinState bitstatus;
+      if((GPIOx->IDR & GPIO_Pin) != (uint32_t)GPIO_PIN_RESET)
+            {
+                    bitstatus = GPIO_PIN_SET;
+                      }
+        else
+              {
+                      bitstatus = GPIO_PIN_RESET;
+                        }
+          return (bitstatus==GPIO_PIN_RESET);
+}
+
+/**************************************************************
+ RATIONALE FOR THIS FUNCTION :
+
+ - The STM32 embeds in ROM a bootloader that allows to
+   obtain code and boot from a number of different interfaces,
+   including USB in a mode called "DFU" (Device Frimware Update)
+   [see AN3606 from ST for full details]
+   This bootloader code is executed instead of the regular
+   application code when pin BOOT0 is pulled-up (which on
+   LimiFrog0.2 is achieved by pressing the general-purpose
+   pushbutton switch on the side.
+ - The bootloader monitors a number of IOs of the STM32 to decide
+   from which interface it should boot.
+ - Problem in LimiFrog (up to versions 0.2a at least): upon
+   power-up the BLE modules generates some activity on UART3,
+   which is part of the pins monitored by the STM32.
+   This misleads the bootloader in trying to boot from UART3
+   and, as a result, not continuing with booting from USB.
+
+  - This code implements an alternative solution to launch the
+  bootloader while making sure UART3 remains stable.
+  - The idea it to start application code with a check, prior to any
+  other applicative code, of whether USB bootload is required (as
+  flagged by a GPIO pulled low at reset, in the same way as BOOT0).
+  The hadware reset pin of BLE is asserted (so that now it won't
+  generate any acitivity on UART3), and if USB bootload is required :
+  bootload ROM is remapped at address 0x0, stack pointer is
+  updated and the code is branched to the start of the bootloader.
+  - This code is run prior to any applicative configuration of clocks,
+  IRQs etc. -- the STM32 is therefore still running from MSI
+
+  THIS FUNCTION MAY BE SUPPRESSED IF YOU NEVER NEED TO BOOT DFU MODE
+
+  ********************************************************************/
+
+static void LBF_DFU_If_Needed(void)
+{
+
+
+ GPIO_InitTypeDef GPIO_InitStruct;
+
+
+   // Initialize and assert pin BTLE_RST
+   // (hw reset to BLE module, so it won't drive UART3)
+
+    __GPIOC_CLK_ENABLE();
+    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+    GPIO_InitStruct.Pull = GPIO_NOPULL;
+    GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
+    GPIO_InitStruct.Pin = BT_RST_PIN;
+    HAL_GPIO_Init(BT_RST_PORT, &GPIO_InitStruct);
+
+    GPIO_HIGH(BT_RST_PORT, BT_RST_PIN); // assert BTLE reset
+
+
+ /* -- Bootloader will be called if position 10 on the extension port
+       is actively pulled low -- */
+       // Note - this is an arbitrary choice, code could be modified to
+       // monitor another GPIO of the STM32 and/or decide that active level
+       // is high rather than low
+
+
+    // Initialize Extension Port Position 10 = PB8 (bears I2C1_SCL)
+    // Use weak pull-up to detect if pin is externally pulled low
+
+    __GPIOB_CLK_ENABLE();
+    GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
+    GPIO_InitStruct.Pull = GPIO_PULLUP;
+    GPIO_InitStruct.Pin = CONN_POS10_PIN;
+    HAL_GPIO_Init(CONN_POS10_PORT, &GPIO_InitStruct);
+
+    // If selection pin pulled low...
+    if ( IS_GPIO_RESET(CONN_POS10_PORT, CONN_POS10_PIN ))
+
+    {
+        // Remap bootloader ROM (ie System Flash) to address 0x0
+        SYSCFG->MEMRMP = 0x00000001;
+
+        // Init stack pointer with value residing at ROM base
+    asm (
+        "LDR     R0, =0x00000000\n\t"  // load ROM base address"
+        "LDR     SP,[R0, #0]\n\t"      // assign main stack pointer"
+        );
+
+        // Jump to address pointed by 0x00000004 -- */
+
+    asm (
+        "LDR     R0,[R0, #4]\n\t"      // load bootloader address
+        "BX      R0\n\t"
+        );
+
+    }
+}

stmhal/boards/LIMIFROG/mpconfigboard.h

@@ -16,6 +16,9 @@
 #define MICROPY_HW_ENABLE_DAC       (0)
 #define MICROPY_HW_ENABLE_CAN       (0)
 
+#define MICROPY_BOARD_EARLY_INIT    LIMIFROG_board_early_init
+void LIMIFROG_board_early_init(void);
+
 // MSI is used and is 4MHz
 #define MICROPY_HW_CLK_PLLM (1)
 #define MICROPY_HW_CLK_PLLN (40)