Commit 54729247 authored by Damien George's avatar Damien George
Browse files

minimal: Add enough code to run minimal build on STM32F4xx hardware.

Minimal support code for a Cortex-M CPU is added, along with set-up
code for an STM32F4xx MCU, including a UART for a REPL.  Tested on
a pyboard.  Code size is 77592 bytes.
parent dd0a0f79
......@@ -19,6 +19,8 @@ INC += -I../stmhal
INC += -I$(BUILD)
ifeq ($(CROSS), 1)
DFU = ../tools/dfu.py
PYDFU = ../tools/pydfu.py
CFLAGS_CORTEX_M4 = -mthumb -mtune=cortex-m4 -mabi=aapcs-linux -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard -fsingle-precision-constant -Wdouble-promotion
CFLAGS = $(INC) -Wall -Werror -ansi -std=gnu99 -nostdlib $(CFLAGS_CORTEX_M4) $(COPT)
else
......@@ -49,20 +51,28 @@ SRC_C = \
lib/libc/string0.c \
lib/mp-readline/readline.c \
SRC_S = \
# startup_stm32f40xx.s \
# gchelper.s \
OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o) $(SRC_S:.s=.o))
OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
ifeq ($(CROSS), 1)
all: $(BUILD)/firmware.dfu
else
all: $(BUILD)/firmware.elf
endif
$(BUILD)/firmware.elf: $(OBJ)
$(ECHO) "LINK $@"
$(Q)$(LD) $(LDFLAGS) -o $@ $^ $(LIBS)
$(Q)$(SIZE) $@
$(BUILD)/firmware.dfu: $(BUILD)/firmware.elf
$(ECHO) "Create $@"
$(Q)$(OBJCOPY) -O binary -j .isr_vector -j .text -j .data $^ $(BUILD)/firmware.bin
$(Q)$(PYTHON) $(DFU) -b 0x08000000:$(BUILD)/firmware.bin $@
deploy: $(BUILD)/firmware.dfu
$(ECHO) "Writing $< to the board"
$(Q)$(PYTHON) $(PYDFU) -u $<
# Run emulation build on a POSIX system with suitable terminal settings
run:
stty raw opost -echo
......
# The minimal port
This port is intended to be a minimal MicroPython port that actually runs.
It can run under Linux (or similar) and on any STM32F4xx MCU (eg the pyboard).
## Building and running Linux version
By default the port will be built for the host machine:
$ make
To run a small test script do:
$ make run
## Building for an STM32 MCU
The Makefile has the ability to build for a Cortex-M CPU, and by default
includes some start-up code for an STM32F4xx MCU and also enables a UART
for communication. To build:
$ make CROSS=1
If you previously built the Linux version, you will need to first run
`make clean` to get rid of incompatible object files.
Building will produce the build/firmware.dfu file which can be programmed
to an MCU using:
$ make CROSS=1 deploy
This version of the build will work out-of-the-box on a pyboard (and
anything similar), and will give you a MicroPython REPL on UART1 at 9600
baud. Pin PA13 will also be driven high, and this turns on the red LED on
the pyboard.
......@@ -94,6 +94,161 @@ void MP_WEAK __assert_func(const char *file, int line, const char *func, const c
}
#endif
#if !MICROPY_MIN_USE_STDOUT
void _start(void) {main(0, NULL);}
#if MICROPY_MIN_USE_CORTEX_CPU
// this is a minimal IRQ and reset framework for any Cortex-M CPU
extern uint32_t _estack, _sidata, _sdata, _edata, _sbss, _ebss;
void Reset_Handler(void) __attribute__((naked));
void Reset_Handler(void) {
// set stack pointer
asm volatile ("ldr sp, =_estack");
// copy .data section from flash to RAM
for (uint32_t *src = &_sidata, *dest = &_sdata; dest < &_edata;) {
*dest++ = *src++;
}
// zero out .bss section
for (uint32_t *dest = &_sbss; dest < &_ebss;) {
*dest++ = 0;
}
// jump to board initialisation
void _start(void);
_start();
}
void Default_Handler(void) {
for (;;) {
}
}
uint32_t isr_vector[] __attribute__((section(".isr_vector"))) = {
(uint32_t)&_estack,
(uint32_t)&Reset_Handler,
(uint32_t)&Default_Handler, // NMI_Handler
(uint32_t)&Default_Handler, // HardFault_Handler
(uint32_t)&Default_Handler, // MemManage_Handler
(uint32_t)&Default_Handler, // BusFault_Handler
(uint32_t)&Default_Handler, // UsageFault_Handler
0,
0,
0,
0,
(uint32_t)&Default_Handler, // SVC_Handler
(uint32_t)&Default_Handler, // DebugMon_Handler
0,
(uint32_t)&Default_Handler, // PendSV_Handler
(uint32_t)&Default_Handler, // SysTick_Handler
};
void _start(void) {
// when we get here: stack is initialised, bss is clear, data is copied
// SCB->CCR: enable 8-byte stack alignment for IRQ handlers, in accord with EABI
*((volatile uint32_t*)0xe000ed14) |= 1 << 9;
// initialise the cpu and peripherals
#if MICROPY_MIN_USE_STM32_MCU
void stm32_init(void);
stm32_init();
#endif
// now that we have a basic system up and running we can call main
main(0, NULL);
// we must not return
for (;;) {
}
}
#endif
#if MICROPY_MIN_USE_STM32_MCU
// this is minimal set-up code for an STM32 MCU
typedef struct {
volatile uint32_t CR;
volatile uint32_t PLLCFGR;
volatile uint32_t CFGR;
volatile uint32_t CIR;
uint32_t _1[8];
volatile uint32_t AHB1ENR;
volatile uint32_t AHB2ENR;
volatile uint32_t AHB3ENR;
uint32_t _2;
volatile uint32_t APB1ENR;
volatile uint32_t APB2ENR;
} periph_rcc_t;
typedef struct {
volatile uint32_t MODER;
volatile uint32_t OTYPER;
volatile uint32_t OSPEEDR;
volatile uint32_t PUPDR;
volatile uint32_t IDR;
volatile uint32_t ODR;
volatile uint16_t BSRRL;
volatile uint16_t BSRRH;
volatile uint32_t LCKR;
volatile uint32_t AFR[2];
} periph_gpio_t;
typedef struct {
volatile uint32_t SR;
volatile uint32_t DR;
volatile uint32_t BRR;
volatile uint32_t CR1;
} periph_uart_t;
#define USART1 ((periph_uart_t*) 0x40011000)
#define GPIOA ((periph_gpio_t*) 0x40020000)
#define GPIOB ((periph_gpio_t*) 0x40020400)
#define RCC ((periph_rcc_t*) 0x40023800)
// simple GPIO interface
#define GPIO_MODE_IN (0)
#define GPIO_MODE_OUT (1)
#define GPIO_MODE_ALT (2)
#define GPIO_PULL_NONE (0)
#define GPIO_PULL_UP (0)
#define GPIO_PULL_DOWN (1)
void gpio_init(periph_gpio_t *gpio, int pin, int mode, int pull, int alt) {
gpio->MODER = (gpio->MODER & ~(3 << (2 * pin))) | (mode << (2 * pin));
// OTYPER is left as default push-pull
// OSPEEDR is left as default low speed
gpio->PUPDR = (gpio->PUPDR & ~(3 << (2 * pin))) | (pull << (2 * pin));
gpio->AFR[pin >> 3] = (gpio->AFR[pin >> 3] & ~(15 << (4 * (pin & 7)))) | (alt << (4 * (pin & 7)));
}
#define gpio_get(gpio, pin) ((gpio->IDR >> (pin)) & 1)
#define gpio_set(gpio, pin, value) do { gpio->ODR = (gpio->ODR & ~(1 << (pin))) | (value << pin); } while (0)
#define gpio_low(gpio, pin) do { gpio->BSRRH = (1 << (pin)); } while (0)
#define gpio_high(gpio, pin) do { gpio->BSRRL = (1 << (pin)); } while (0)
void stm32_init(void) {
// basic MCU config
RCC->CR |= (uint32_t)0x00000001; // set HSION
RCC->CFGR = 0x00000000; // reset all
RCC->CR &= (uint32_t)0xfef6ffff; // reset HSEON, CSSON, PLLON
RCC->PLLCFGR = 0x24003010; // reset PLLCFGR
RCC->CR &= (uint32_t)0xfffbffff; // reset HSEBYP
RCC->CIR = 0x00000000; // disable IRQs
// leave the clock as-is (internal 16MHz)
// enable GPIO clocks
RCC->AHB1ENR |= 0x00000003; // GPIOAEN, GPIOBEN
// turn on an LED! (on pyboard it's the red one)
gpio_init(GPIOA, 13, GPIO_MODE_OUT, GPIO_PULL_NONE, 0);
gpio_high(GPIOA, 13);
// enable UART1 at 9600 baud (TX=B6, RX=B7)
gpio_init(GPIOB, 6, GPIO_MODE_ALT, GPIO_PULL_NONE, 7);
gpio_init(GPIOB, 7, GPIO_MODE_ALT, GPIO_PULL_NONE, 7);
RCC->APB2ENR |= 0x00000010; // USART1EN
USART1->BRR = (104 << 4) | 3; // 16MHz/(16*104.1875) = 9598 baud
USART1->CR1 = 0x0000200c; // USART enable, tx enable, rx enable
}
#endif
......@@ -83,6 +83,11 @@ extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_MIN_USE_STDOUT (1)
#endif
#ifdef __thumb__
#define MICROPY_MIN_USE_CORTEX_CPU (1)
#define MICROPY_MIN_USE_STM32_MCU (1)
#endif
#define MP_STATE_PORT MP_STATE_VM
#define MICROPY_PORT_ROOT_POINTERS \
......
......@@ -6,8 +6,6 @@
MEMORY
{
FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 0x100000 /* entire flash, 1 MiB */
FLASH_ISR (rx) : ORIGIN = 0x08000000, LENGTH = 0x004000 /* sector 0, 16 KiB */
FLASH_TEXT (rx) : ORIGIN = 0x08020000, LENGTH = 0x080000 /* sectors 5,6,7,8, 4*128KiB = 512 KiB (could increase it more) */
CCMRAM (xrw) : ORIGIN = 0x10000000, LENGTH = 0x010000 /* 64 KiB */
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 0x020000 /* 128 KiB */
}
......@@ -15,52 +13,24 @@ MEMORY
/* top end of the stack */
_estack = ORIGIN(RAM) + LENGTH(RAM);
/* RAM extents for the garbage collector */
_ram_end = ORIGIN(RAM) + LENGTH(RAM);
_heap_end = 0x2001c000; /* tunable */
/* define output sections */
SECTIONS
{
/* The startup code goes first into FLASH */
.isr_vector :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} >FLASH_ISR
/* The program code and other data goes into FLASH */
.text :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* isr vector table */
*(.text) /* .text sections (code) */
*(.text*) /* .text* sections (code) */
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
/* *(.glue_7) */ /* glue arm to thumb code */
/* *(.glue_7t) */ /* glue thumb to arm code */
. = ALIGN(4);
_etext = .; /* define a global symbol at end of code */
_sidata = _etext; /* This is used by the startup in order to initialize the .data secion */
} >FLASH_TEXT
/*
.ARM.extab :
{
*(.ARM.extab* .gnu.linkonce.armextab.*)
} >FLASH
.ARM :
{
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
} >FLASH
*/
/* This is the initialized data section
The program executes knowing that the data is in the RAM
but the loader puts the initial values in the FLASH (inidata).
......@@ -69,7 +39,6 @@ SECTIONS
{
. = ALIGN(4);
_sdata = .; /* create a global symbol at data start; used by startup code in order to initialise the .data section in RAM */
_ram_start = .; /* create a global symbol at ram start for garbage collector */
*(.data) /* .data sections */
*(.data*) /* .data* sections */
......@@ -90,28 +59,5 @@ SECTIONS
_ebss = .; /* define a global symbol at bss end; used by startup code */
} >RAM
/* this is to define the start of the heap, and make sure we have a minimum size */
.heap :
{
. = ALIGN(4);
_heap_start = .; /* define a global symbol at heap start */
} >RAM
/* this just checks there is enough RAM for the stack */
.stack :
{
. = ALIGN(4);
} >RAM
/* Remove information from the standard libraries */
/*
/DISCARD/ :
{
libc.a ( * )
libm.a ( * )
libgcc.a ( * )
}
*/
.ARM.attributes 0 : { *(.ARM.attributes) }
}
......@@ -5,12 +5,25 @@
* Core UART functions to implement for a port
*/
#if MICROPY_MIN_USE_STM32_MCU
typedef struct {
volatile uint32_t SR;
volatile uint32_t DR;
} periph_uart_t;
#define USART1 ((periph_uart_t*)0x40011000)
#endif
// Receive single character
int mp_hal_stdin_rx_chr(void) {
unsigned char c = 0;
#if MICROPY_MIN_USE_STDOUT
int r = read(0, &c, 1);
(void)r;
#elif MICROPY_MIN_USE_STM32_MCU
// wait for RXNE
while ((USART1->SR & (1 << 5)) == 0) {
}
c = USART1->DR;
#endif
return c;
}
......@@ -20,5 +33,12 @@ void mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
#if MICROPY_MIN_USE_STDOUT
int r = write(1, str, len);
(void)r;
#elif MICROPY_MIN_USE_STM32_MCU
while (len--) {
// wait for TXE
while ((USART1->SR & (1 << 7)) == 0) {
}
USART1->DR = *str++;
}
#endif
}
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