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

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

‎stmhal/boards/LIMIFROG/mpconfigboard.h‎

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#define MICROPY_HW_ENABLE_DAC (0)
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#define MICROPY_HW_ENABLE_CAN (0)
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#define MICROPY_BOARD_EARLY_INIT LIMIFROG_board_early_init
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void LIMIFROG_board_early_init(void);
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// MSI is used and is 4MHz
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#define MICROPY_HW_CLK_PLLM (1)
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#define MICROPY_HW_CLK_PLLN (40)

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