Add STM32F103 port

Add a fully functional STM32F1 port, currently mostly targeting STM32F103
microcontrollers. This requires an 8 MHz XTAL. The maximum possible step rate
is around 282K steps per second.

This uses stm32flash to burn the firmware. The bootloader needs to be started
by setting BOOT0 to 1 and resetting the MCU. There is no automatic bootloader,
unlike on Arduino.

Signed-off-by: Grigori Goronzy <greg@kinoho.net>

1 files changed, 136 insertions, 0 deletions

diff --git a/src/stm32f1/main.c b/src/stm32f1/main.c
new file mode 100644
index 00000000..8c144343
--- /dev/null
+++ b/src/stm32f1/main.c
@@ -0,0 +1,136 @@
+// Main starting point for STM32F103 boards.
+//
+// Copyright (C) 2018 Grigori Goronzy <greg@kinoho.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "autoconf.h"
+#include "command.h" // DECL_CONSTANT
+#include "stm32f1xx.h"
+#include "stm32f1xx_ll_system.h"
+#include "stm32f1xx_ll_utils.h"
+#include "stm32f1xx_ll_bus.h"
+#include "stm32f1xx_ll_rcc.h"
+#include "stm32f1xx_ll_iwdg.h"
+#include "stm32f1xx_ll_gpio.h"
+#include "stm32f1xx_ll_adc.h"
+#include "sched.h" // sched_main
+
+DECL_CONSTANT(MCU, "stm32f103");
+
+/****************************************************************
+ * dynamic memory pool
+ ****************************************************************/
+
+static char dynmem_pool[15 * 1024];
+
+// Return the start of memory available for dynamic allocations
+void *
+dynmem_start(void)
+{
+    return dynmem_pool;
+}
+
+// Return the end of memory available for dynamic allocations
+void *
+dynmem_end(void)
+{
+    return &dynmem_pool[sizeof(dynmem_pool)];
+}
+
+
+/****************************************************************
+ * watchdog handler
+ ****************************************************************/
+
+void
+watchdog_reset(void)
+{
+    LL_IWDG_ReloadCounter(IWDG);
+}
+DECL_TASK(watchdog_reset);
+
+void
+watchdog_init(void)
+{
+    LL_IWDG_EnableWriteAccess(IWDG);
+    /* IWDG timer is 40 KHz, configure to trigger every seconds */
+    LL_IWDG_SetPrescaler(IWDG, LL_IWDG_PRESCALER_16);
+    LL_IWDG_SetReloadCounter(IWDG, 2500);
+    LL_IWDG_Enable(IWDG);
+
+}
+DECL_INIT(watchdog_init);
+
+
+/****************************************************************
+ * misc functions
+ ****************************************************************/
+
+void
+command_reset(uint32_t *args)
+{
+    NVIC_SystemReset();
+}
+DECL_COMMAND_FLAGS(command_reset, HF_IN_SHUTDOWN, "reset");
+
+void clock_config(void)
+{
+    LL_RCC_HSE_Enable();
+    while (!LL_RCC_HSE_IsReady());
+    LL_RCC_PLL_ConfigDomain_SYS(LL_RCC_PLLSOURCE_HSE, LL_RCC_PLL_MUL_9);
+    LL_RCC_PLL_Disable();
+    LL_RCC_PLL_Enable();
+    while (!LL_RCC_PLL_IsReady());
+    LL_RCC_SetAHBPrescaler(LL_RCC_SYSCLK_DIV_1);
+    LL_RCC_SetAPB1Prescaler(LL_RCC_APB1_DIV_2);
+    LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_2);
+    LL_RCC_SetADCClockSource(LL_RCC_ADC_CLKSRC_PCLK2_DIV_4);
+    LL_FLASH_SetLatency(LL_FLASH_LATENCY_2);
+    LL_FLASH_EnablePrefetch();
+    LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_PLL);
+    SystemCoreClockUpdate();
+    LL_Init1msTick(SystemCoreClock);
+}
+
+void adc_config(void)
+{
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_ADC1);
+    /* ADC might be in deep sleep, needs to be woken up twice in that case */
+    LL_ADC_Enable(ADC1);
+    LL_mDelay(1);
+    LL_ADC_Enable(ADC1);
+    LL_mDelay(1);
+    LL_ADC_StartCalibration(ADC1);
+    while (LL_ADC_IsCalibrationOnGoing(ADC1));
+    LL_ADC_SetSequencersScanMode(ADC1, LL_ADC_SEQ_SCAN_DISABLE);
+    LL_ADC_REG_SetTriggerSource(ADC1, LL_ADC_REG_TRIG_SOFTWARE);
+    LL_ADC_REG_SetSequencerLength(ADC1, LL_ADC_REG_SEQ_SCAN_DISABLE);
+}
+
+void io_config(void)
+{
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_AFIO);
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_GPIOA);
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_GPIOB);
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_GPIOC);
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_GPIOD);
+    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_GPIOE);
+    /* JTAG is normally not needed, but blocks ports like PB3, PB4 */
+    LL_GPIO_AF_Remap_SWJ_NOJTAG();
+    /* Likewise, we don't need PB3 for TRACESWO output */
+    LL_DBGMCU_SetTracePinAssignment(LL_DBGMCU_TRACE_NONE);
+}
+
+// Main entry point
+int
+main(void)
+{
+    SystemInit();
+    LL_Init1msTick(SystemCoreClock);
+    clock_config();
+    adc_config();
+    io_config();
+    sched_main();
+    return 0;
+}