pi-pico: initial blink example

pi-pico/blink/Makefile

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+CC = arm-none-eabi-gcc
+AS = arm-none-eabi-as
+LD = arm-none-eabi-ld
+
+OBJDUMP = arm-none-eabi-objdump
+OBJCOPY = arm-none-eabi-objcopy
+#CFLAGS = -g -O2 -Wall
+CFLAGS = -g -O3 -Wall -I..
+CFLAGS += -mlittle-endian -mthumb -mcpu=cortex-m0plus
+CFLAGS += -fno-common
+CFLAGS += -ffunction-sections -fdata-sections
+ASFLAGS =
+
+ELF2UF2	= ../elf2uf2/elf2uf2
+
+##### Project specific libraries #####
+SRC_FILES = blink.c
+
+all:  blink.uf2 blink.dis
+
+clean:
+	rm -f blink.bin blink.elf *~ *.o *.dis *.uf2
+
+crt0.o:	crt0.S
+	$(AS) $(ASFLAGS) -o crt0.o -c crt0.S
+
+#boot2_w25q080.o:	boot2_w25q080.S
+#	$(AS) $(ASFLAGS) -o boot2_w25q080.o -c boot2_w25q080.S
+
+idivmod.o:	idivmod.S
+	$(AS) $(ASFLAGS) -o idivmod.o -c idivmod.S
+
+uldivmod.o:	uldivmod.S
+	$(AS) $(ASFLAGS) -o uldivmod.o -c uldivmod.S
+
+runtime.o:	runtime.c
+	$(CC) $(CFLAGS) -c runtime.c
+
+blink.elf: blink.o crt0.o bootrom.o runtime.o clocks.o gpio.o idivmod.o uldivmod.o
+	$(LD) -v -Tmemmap_default.ld -nostartfiles -o blink.elf blink.o \
+		bootrom.o crt0.o \
+		runtime.o clocks.o gpio.o idivmod.o uldivmod.o
+#		boot2_w25q080.o 
+
+bootrom.o:	bootrom.c
+	$(CC) $(CFLAGS) -c bootrom.c
+
+clocks.o:	clocks.c
+	$(CC) $(CFLAGS) -c clocks.c
+
+blink.o:	blink.c
+	$(CC) $(CFLAGS) -c blink.c
+
+blink.uf2: blink.elf
+	$(ELF2UF2) blink.elf blink.uf2
+
+blink.dis:	blink.elf
+	$(OBJDUMP) -h blink.elf > blink.dis
+	$(OBJDUMP) -d blink.elf >> blink.dis
+
+####
+
+gpio.o:	gpio.c ../include/gpio.h
+	$(CC) $(CFLAGS) -c gpio.c
+
+

pi-pico/blink/README

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+
+Packages to install:
+
+
+Setup:
+
+Flashing:
+~~~~~~~~~
++ Haven't got the drag-and-drop method going, but using the SWD method.
+
+	From the "getting started w Raspberry Pi Pico" document
+
+	Set up a Pi4 to be the host, and wire up according to the diagram.
+
+	git clone https://github.com/raspberrypi/openocd.git --recursive --branch rp2040 --depth=1
+	cd openocd
+	./bootstrap
+	./configure --enable-ftdi --enable-sysfsgpio --enable-bcm2835gpio
+	make -j4
+	sudo make install
+
+	openocd -f interface/raspberrypi-swd.cfg -f target/rp2040.cfg -c "program blink/blink.elf verify reset exit"

pi-pico/blink/blink.c

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+#include <stdint.h>
+
+#include "include/pi-pico.h"
+#include "include/gpio.h"
+
+typedef uint64_t absolute_time_t;
+
+static void tight_loop_contents(void) {}
+
+#define TIMER_BASE 0x40054000
+
+
+#define NUM_TIMERS 4
+
+typedef volatile uint32_t io_rw_32;
+typedef const volatile uint32_t io_ro_32;
+typedef volatile uint32_t io_wo_32;
+
+typedef struct {
+    io_wo_32 timehw;
+    io_wo_32 timelw;
+    io_ro_32 timehr;
+    io_ro_32 timelr;
+    io_rw_32 alarm[NUM_TIMERS];
+    io_rw_32 armed;
+    io_ro_32 timerawh;
+    io_ro_32 timerawl;
+    io_rw_32 dbgpause;
+    io_rw_32 pause;
+    io_rw_32 intr;
+    io_rw_32 inte;
+    io_rw_32 intf;
+    io_ro_32 ints;
+} timer_hw_t;
+
+#define timer_hw ((timer_hw_t *const)TIMER_BASE)
+
+
+static uint64_t to_us_since_boot(absolute_time_t t) {
+    return t;
+}
+
+
+static void update_us_since_boot(absolute_time_t *t, uint64_t us_since_boot) {
+//#ifdef NDEBUG
+    *t = us_since_boot;
+//#else
+//    assert(us_since_boot <= INT64_MAX);
+//    t->_private_us_since_boot = us_since_boot;
+//#endif
+}
+
+
+uint64_t time_us_64(void) {
+    // Need to make sure that the upper 32 bits of the timer
+    // don't change, so read that first
+    uint32_t hi = timer_hw->timerawh;
+    uint32_t lo;
+    do {
+        // Read the lower 32 bits
+        lo = timer_hw->timerawl;
+        // Now read the upper 32 bits again and
+        // check that it hasn't incremented. If it has loop around
+        // and read the lower 32 bits again to get an accurate value
+        uint32_t next_hi = timer_hw->timerawh;
+        if (hi == next_hi) break;
+        hi = next_hi;
+    } while (1);
+    return ((uint64_t) hi << 32u) | lo;
+}
+
+
+void busy_wait_until(absolute_time_t t) {
+    uint64_t target = to_us_since_boot(t);
+    uint32_t hi_target = (uint32_t)(target >> 32u);
+    uint32_t hi = timer_hw->timerawh;
+    while (hi < hi_target) {
+        hi = timer_hw->timerawh;
+        tight_loop_contents();
+    }
+    while (hi == hi_target && timer_hw->timerawl < (uint32_t) target) {
+        hi = timer_hw->timerawh;
+        tight_loop_contents();
+    }
+}
+
+
+void busy_wait_us(uint64_t delay_us) {
+    uint64_t base = time_us_64();
+    uint64_t target = base + delay_us;
+    if (target < base) {
+        target = (uint64_t)-1;
+    }
+    absolute_time_t t;
+    update_us_since_boot(&t, target);
+    busy_wait_until(t);
+}
+
+
+void busy_wait_us_32(uint32_t delay_us) {
+    if (0 <= (int32_t)delay_us) {
+        // we only allow 31 bits, otherwise we could have a race in the loop below with
+        // values very close to 2^32
+        uint32_t start = timer_hw->timerawl;
+        while (timer_hw->timerawl - start < delay_us) {
+            tight_loop_contents();
+        }
+    } else {
+        busy_wait_us(delay_us);
+    }
+}
+
+static absolute_time_t get_absolute_time(void) {
+    absolute_time_t t;
+    update_us_since_boot(&t, time_us_64());
+    return t;
+}
+
+
+static inline absolute_time_t delayed_by_us(const absolute_time_t t, uint64_t us) {
+    absolute_time_t t2;
+    uint64_t base = to_us_since_boot(t);
+    uint64_t delayed = base + us;
+    if (delayed < base) {
+        delayed = (uint64_t)-1;
+    }
+    update_us_since_boot(&t2, delayed);
+    return t2;
+}
+
+
+static absolute_time_t make_timeout_time_us(uint64_t us) {
+    return delayed_by_us(get_absolute_time(), us);
+}
+
+
+void sleep_us(uint64_t us) {
+//#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
+//    sleep_until(make_timeout_time_us(us));
+//#else
+    if (us >> 32u) {
+        busy_wait_until(make_timeout_time_us(us));
+    } else {
+        busy_wait_us_32(us);
+    }
+//#endif
+
+}
+
+void sleep_ms(uint32_t ms) {
+    sleep_us(ms * 1024ull);	// FIXME
+}
+
+
+int main(int argc, char **argv) {
+
+	const uint32_t LED_PIN = PICO_DEFAULT_LED_PIN;
+
+	gpio_init(LED_PIN);
+	gpio_set_dir(LED_PIN, GPIO_OUT);
+
+	while (1) {
+		gpio_put(LED_PIN, 1);
+		sleep_ms(250);
+		gpio_put(LED_PIN, 0);
+		sleep_ms(250);
+	}
+
+	return 0;
+
+}

pi-pico/blink/bootrom.c

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+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdint.h>
+
+//#include "pico/bootrom.h"
+
+/// \tag::table_lookup[]
+
+// Bootrom function: rom_table_lookup
+// Returns the 32 bit pointer into the ROM if found or NULL otherwise.
+typedef void *(*rom_table_lookup_fn)(uint16_t *table, uint32_t code);
+
+// Convert a 16 bit pointer stored at the given rom address into a 32 bit pointer
+#define rom_hword_as_ptr(rom_address) (void *)(uintptr_t)(*(uint16_t *)rom_address)
+
+void *rom_func_lookup(uint32_t code) {
+    rom_table_lookup_fn rom_table_lookup = (rom_table_lookup_fn) rom_hword_as_ptr(0x18);
+    uint16_t *func_table = (uint16_t *) rom_hword_as_ptr(0x14);
+    return rom_table_lookup(func_table, code);
+}
+
+void *rom_data_lookup(uint32_t code) {
+    rom_table_lookup_fn rom_table_lookup = (rom_table_lookup_fn) rom_hword_as_ptr(0x18);
+    uint16_t *data_table = (uint16_t *) rom_hword_as_ptr(0x16);
+    return rom_table_lookup(data_table, code);
+}
+/// \end::table_lookup[]
+
+int rom_funcs_lookup(uint32_t *table, unsigned int count) {
+    int ok = 1;
+    for (unsigned int i = 0; i < count; i++) {
+        table[i] = (uintptr_t) rom_func_lookup(table[i]);
+        if (!table[i]) ok = 0;
+    }
+    return ok;
+}

pi-pico/blink/bs2_default_padded_checksummed.S

@@ -0,0 +1,23 @@
+// Padded and checksummed version of: /home/vince/research/vmw-meter.git/pi-pico/pico/pico-examples/build/pico-sdk/src/rp2_common/boot_stage2/bs2_default.bin
+
+.cpu cortex-m0plus
+.thumb
+
+.section .boot2, "ax"
+
+.byte 0x00, 0xb5, 0x32, 0x4b, 0x21, 0x20, 0x58, 0x60, 0x98, 0x68, 0x02, 0x21, 0x88, 0x43, 0x98, 0x60
+.byte 0xd8, 0x60, 0x18, 0x61, 0x58, 0x61, 0x2e, 0x4b, 0x00, 0x21, 0x99, 0x60, 0x02, 0x21, 0x59, 0x61
+.byte 0x01, 0x21, 0xf0, 0x22, 0x99, 0x50, 0x2b, 0x49, 0x19, 0x60, 0x01, 0x21, 0x99, 0x60, 0x35, 0x20
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+.byte 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x07, 0x00, 0x00, 0x03, 0x5f, 0x00, 0x21, 0x22, 0x00, 0x00
+.byte 0xf4, 0x00, 0x00, 0x18, 0x22, 0x20, 0x00, 0xa0, 0x00, 0x01, 0x00, 0x10, 0x08, 0xed, 0x00, 0xe0
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