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-rw-r--r--02-usart/src/arch/stm32l4xxx/peripherals/clock.c1
-rw-r--r--02-usart/src/arch/stm32l4xxx/peripherals/gpio.c52
-rw-r--r--02-usart/src/arch/stm32l4xxx/peripherals/irq.c26
-rw-r--r--02-usart/src/kern/dma/dma_manager.c1
-rw-r--r--02-usart/src/kern/gpio/gpio_manager.c402
-rw-r--r--02-usart/src/kern/gpio/sysled.c14
-rw-r--r--02-usart/src/kern/main.c39
-rw-r--r--02-usart/src/kern/spin.c49
8 files changed, 454 insertions, 130 deletions
diff --git a/02-usart/src/arch/stm32l4xxx/peripherals/clock.c b/02-usart/src/arch/stm32l4xxx/peripherals/clock.c
index ba127a9..1029d39 100644
--- a/02-usart/src/arch/stm32l4xxx/peripherals/clock.c
+++ b/02-usart/src/arch/stm32l4xxx/peripherals/clock.c
@@ -6,7 +6,6 @@
#include "arch/stm32l4xxx/peripherals/flash.h"
#include <stdint.h>
-#include "kern/spin.h"
#define TIMEOUT 10000
diff --git a/02-usart/src/arch/stm32l4xxx/peripherals/gpio.c b/02-usart/src/arch/stm32l4xxx/peripherals/gpio.c
deleted file mode 100644
index a1e82c7..0000000
--- a/02-usart/src/arch/stm32l4xxx/peripherals/gpio.c
+++ /dev/null
@@ -1,52 +0,0 @@
-#include "arch/stm32l4xxx/peripherals/gpio.h"
-#include "arch/stm32l4xxx/peripherals/rcc.h"
-
-/*
- * Sets the mode of a pin on a gpio por.
- */
-void set_gpio_pin_mode(
- __IO gpio_port_t* gpio_port, gpio_pin_t pin, gpio_pin_mode_t mode)
-{
- /* Each pin has a 2-bit mode provided at bits pin#*2 and pin#*2+1 */
- gpio_port->mode_r &= ~(0x03 << pin * 2);
- gpio_port->mode_r |= mode << pin * 2;
-}
-
-gpio_output_pin_t set_gpio_pin_output(
- __IO gpio_port_t* gpio_port, gpio_pin_t pin)
-{
- set_gpio_pin_mode(gpio_port, pin, MODE_OUTPUT);
-
- return (gpio_output_pin_t){.gpio_port = gpio_port, .pin = pin};
-}
-
-void set_gpio_output_pin(gpio_output_pin_t pin, bool onoff)
-{
- if (onoff) {
- pin.gpio_port->output_r |= 1 << pin.pin;
- } else {
- pin.gpio_port->output_r &= ~(1 << pin.pin);
- }
-}
-
-void set_gpio_alternate_function(
- __IO gpio_port_t* port, gpio_pin_t gpio_pin, alternate_function_t afn)
-{
- __IO uint32_t* reg;
- if (gpio_pin < 8) {
- reg = &(port->af_rl);
- } else {
- reg = &(port->af_rh);
- gpio_pin -= 8;
- }
-
- uint32_t tmp = *reg & (~0x0f << gpio_pin * 4);
- *reg = tmp | (afn << gpio_pin * 4);
-}
-
-#define GPIO_PORTS_BASE_ADDR ((uint8_t*)0x48000000)
-__IO gpio_port_t* enable_gpio(gpio_port_number_t gpio_port_number)
-{
- RCC.ahb2en_r |= 1 << gpio_port_number; /* Enable the GPIO port. */
- return (__IO gpio_port_t*)(GPIO_PORTS_BASE_ADDR + (gpio_port_number * 0x400));
-}
diff --git a/02-usart/src/arch/stm32l4xxx/peripherals/irq.c b/02-usart/src/arch/stm32l4xxx/peripherals/irq.c
index 8fb3e49..364b9a7 100644
--- a/02-usart/src/arch/stm32l4xxx/peripherals/irq.c
+++ b/02-usart/src/arch/stm32l4xxx/peripherals/irq.c
@@ -4,6 +4,7 @@
#include "arch.h"
#include "kern/delay.h"
+#include "kern/gpio/gpio_manager.h"
#define IRQ_RESERVED(n)
#define IRQ(name, uname_, n) \
@@ -16,10 +17,11 @@
void isr_simple_pin_on()
{
- __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
- gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
+ int ec;
+ gpio_pin_opts_t opts = DEFAULT_GPIO_OPTS_OUTPUT;
+ gpio_reserved_pin_t pin3 = reserve_gpio_pin(GPIO_PIN_PB3, &opts, &ec);
- pin_on(pin3);
+ set_gpio_pin_high(pin3);
}
#define IRQ_RESERVED(n) 0,
@@ -47,13 +49,15 @@ const void* vectors[] __attribute__((section(".vectors"))) = {
*/
void unhandled_isr(uint8_t number)
{
- __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
- gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
+ int ec;
+ gpio_pin_opts_t opts = DEFAULT_GPIO_OPTS_OUTPUT;
+ gpio_reserved_pin_t pin3 = reserve_gpio_pin(GPIO_PIN_PB3, &opts, &ec);
+
for (;;) {
for (int i = 0; i < 20; ++ i) {
- pin_on(pin3);
+ set_gpio_pin_high(pin3);
delay(1000000);
- pin_off(pin3);
+ set_gpio_pin_low(pin3);
delay(1000000);
}
delay(50000000);
@@ -62,15 +66,15 @@ void unhandled_isr(uint8_t number)
for (int i = 0; i < 8; ++ i) {
if (n & 1) {
// LSB is a 1
- pin_on(pin3);
+ set_gpio_pin_high(pin3);
delay(15000000);
- pin_off(pin3);
+ set_gpio_pin_low(pin3);
delay(15000000);
} else {
// LSB is a 0
- pin_on(pin3);
+ set_gpio_pin_high(pin3);
delay(1000000);
- pin_off(pin3);
+ set_gpio_pin_low(pin3);
delay(29000000);
}
diff --git a/02-usart/src/kern/dma/dma_manager.c b/02-usart/src/kern/dma/dma_manager.c
index 4336496..00e9f3d 100644
--- a/02-usart/src/kern/dma/dma_manager.c
+++ b/02-usart/src/kern/dma/dma_manager.c
@@ -75,7 +75,6 @@ static int try_reserve_dma_channel(
return !(in_use & (1 << chan.chan));
}
- // int in_use = __sync_fetch_and_or(&dma_inuse[dmasel], 1 << chan);
void release_dma_channel(dma_channel_t chan)
{
dma_channel_config_t* config = get_raw_channel_config(chan);
diff --git a/02-usart/src/kern/gpio/gpio_manager.c b/02-usart/src/kern/gpio/gpio_manager.c
new file mode 100644
index 0000000..82dd0ba
--- /dev/null
+++ b/02-usart/src/kern/gpio/gpio_manager.c
@@ -0,0 +1,402 @@
+#include "kern/gpio/gpio_manager.h"
+
+#include "arch/stm32l4xxx/peripherals/irq.h"
+#include "arch/stm32l4xxx/peripherals/rcc.h"
+
+/* A list of whether the pins are in use or not as a bitmask. */
+uint32_t pins_inuse[N_GPIO_PINS / 32 + (N_GPIO_PINS % 32 != 0)];
+
+struct gpio_afn_and_pin {
+ int8_t afn_number;
+ gpio_pin_t gpio_pin;
+};
+
+/*
+ * Returns which (pin, afn) pairs provide the given alternate function.
+ * The out array needs to have 5 positions.
+ *
+ * This function will use afn_number = -1 as the terminal.
+ *
+ * Note that EVENTOUT is a special case because all pins have an event out
+ * at afn=15 and should be assumed by other logic and thus is not handled
+ * by this function.
+ */
+static void get_ports_and_pins_for_alternate_function(
+ gpio_alternate_function_t afn, struct gpio_afn_and_pin* out)
+{
+ switch (afn) {
+#define AFN1(fn, ...) \
+ static_assert(false, "Unable to parse afn_table at " #fn);
+#define AFN3(fn, ...) \
+ static_assert(false, "Unable to parse afn_table at " #fn);
+#define AFN5(fn, ...) \
+ static_assert(false, "Unable to parse afn_table at " #fn);
+#define AFN7(fn, ...) \
+ static_assert(false, "Unable to parse afn_table at " #fn);
+
+#define AFN2(fn, afn, pin) \
+ out[0].afn_number = afn; \
+ out[0].gpio_pin = GPIO_PIN_ ## pin
+
+#define AFN4(fn, afn0, pin0, afn1, pin1) \
+ AFN2(fn, afn0, pin0); \
+ out[1].afn_number = afn1; \
+ out[1].gpio_pin = GPIO_PIN_ ## pin1
+
+#define AFN6(fn, afn0, pin0, afn1, pin1, afn2, pin2) \
+ AFN4(fn, afn0, pin0, afn1, pin1); \
+ out[2].afn_number = afn2; \
+ out[2].gpio_pin = GPIO_PIN_ ## pin2
+
+#define AFN8(fn, afn0, pin0, afn1, pin1, afn2, pin2, afn3, pin3) \
+ AFN6(fn, afn0, pin0, afn1, pin1, afn2, pin2); \
+ out[2].afn_number = afn3; \
+ out[2].gpio_pin = GPIO_PIN_ ## pin3
+
+#define GET_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, NAME, ...) NAME
+#define GET_N(_1, _2, _3, _4, _5, _6, _7, _8, NAME, ...) NAME
+#define AFN(fn, ...) \
+ case GPIO_ALTERNATE_FUNCTION_ ## fn: \
+ GET_MACRO(__VA_ARGS__, AFN8, AFN7, AFN6, AFN5, AFN4, AFN3, AFN2, AFN1)\
+ (fn, __VA_ARGS__); \
+ out[GET_N(__VA_ARGS__, 4, 4, 3, 3, 2, 2, 1, 1)] = \
+ (struct gpio_afn_and_pin){-1, -1}; \
+ break;
+
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/afn_table.inc"
+ case GPIO_ALTERNATE_FUNCTION_EVENTOUT:
+ return;
+ }
+}
+
+static inline int offset_for_gpio_pin(gpio_pin_t pin)
+{
+ switch (pin) {
+#define PORT(p, pn) \
+ case GPIO_PIN_P ## p ## pn: return pn;
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+#undef PORT
+ case N_GPIO_PINS: return -1;
+ }
+
+ /* Should be unreachable. */
+ return -1;
+}
+
+inline bool gpio_pin_in_use(gpio_pin_t pin)
+{
+ return !!(pins_inuse[pin / 32] & (1 << (pin % 32)));
+}
+
+#define A(...)
+#define B(...)
+#define C(...)
+#define D(...)
+#define E(...)
+#define F(...)
+#define G(...)
+#define H(...)
+#define I(...)
+#define SELECT_MACRO(PORT) PORT
+#define PORT(port, pin) \
+ SELECT_MACRO(port)(GPIO_PIN_P ## port ## pin, pin)
+static int gc_port_a()
+{
+ return 0
+#undef A
+#define A(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef A
+#define A(...)
+}
+
+static int gc_port_b()
+{
+ return 0
+#undef B
+#define B(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef B
+#define B(...)
+}
+
+static int gc_port_c()
+{
+ return 0
+#undef C
+#define C(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef C
+#define C(...)
+}
+
+static int gc_port_d()
+{
+ return 0
+#undef D
+#define D(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef D
+#define D(...)
+}
+
+static int gc_port_e()
+{
+ return 0
+#undef E
+#define E(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef E
+#define E(...)
+}
+
+static int gc_port_f()
+{
+ return 0
+#undef F
+#define F(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef F
+#define F(...)
+}
+
+static int gc_port_g()
+{
+ return 0
+#undef G
+#define G(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef G
+#define G(...)
+}
+
+static int gc_port_h()
+{
+ return 0
+#undef H
+#define H(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef H
+#define H(...)
+}
+
+static int gc_port_i()
+{
+ return 0
+#undef I
+#define I(abspin, relpin) \
+ | (gpio_pin_in_use(abspin) << (relpin))
+#include "arch/stm32l4xxx/peripherals/tables/stm32l432xx/gpio/port_table.inc"
+ ;
+#undef I
+#define I(...)
+}
+
+
+static inline bool gpio_pin_try_reserve(gpio_pin_t pin)
+{
+ int in_use = __sync_fetch_and_or(
+ &pins_inuse[pin / 32], 1 << (pin % 32));
+ return !(in_use & (1 << (pin % 32)));
+}
+
+inline static gpio_port_config_t* get_gpio_port_config(gpio_port_t port)
+{
+ switch(port) {
+ case GPIO_PORT_A: return (gpio_port_config_t*) GPIOA_BASE;
+ case GPIO_PORT_B: return (gpio_port_config_t*) GPIOB_BASE;
+ case GPIO_PORT_C: return (gpio_port_config_t*) GPIOC_BASE;
+ case GPIO_PORT_H: return (gpio_port_config_t*) GPIOH_BASE;
+ default: return NULL;
+ }
+}
+
+inline static gpio_port_config_t* get_gpio_port_config_for_pin(gpio_pin_t pin)
+{
+ gpio_port_t port = get_port_for_pin(pin);
+ return get_gpio_port_config(port);
+}
+
+gpio_reserved_pin_t reserve_gpio_pin(
+ gpio_pin_t pin, gpio_pin_opts_t* opts, int* error_out)
+{
+ *error_out = 0;
+ if (!gpio_pin_try_reserve(pin)) {
+ *error_out = GPIO_ERROR_IN_USE;
+ return (gpio_reserved_pin_t) { .v_ = -1 };
+ }
+
+ gpio_port_t port = get_port_for_pin(pin);
+ regset(RCC.ahb2en_r, rcc_gpioen(port), 1);
+
+ gpio_port_config_t* port_config = get_gpio_port_config(port);
+
+
+ int off = offset_for_gpio_pin(pin);
+
+ regset(port_config->mode_r, gpio_mode_n(off), opts->mode);
+ regset(port_config->pupd_r, gpio_pupd_n(off), opts->pull_dir);
+
+ switch(opts->mode) {
+ case GPIO_MODE_INPUT:
+ break;
+
+ case GPIO_MODE_OUTPUT:
+ regset(port_config->ospeed_r, gpio_ospeed_n(off), opts->output_opts.speed);
+ regset(port_config->otype_r, gpio_otype_n(off), opts->output_opts.type);
+ break;
+
+ case GPIO_MODE_ALTERNATE:
+ if (off < 8) {
+ regset(
+ port_config->af_rl,
+ gpio_afsel_n(off),
+ opts->alternate_opts.function);
+ } else {
+ regset(
+ port_config->af_rh,
+ gpio_afsel_n(off - 8),
+ opts->alternate_opts.function);
+ }
+ break;
+
+ case GPIO_MODE_ANALOG:
+ regset(port_config->asc_r, gpio_asc_n(off), 1);
+ break;
+ }
+
+ return (gpio_reserved_pin_t) { .v_ = pin };
+}
+
+gpio_reserved_pin_t gpio_enable_alternate_function(
+ gpio_alternate_function_t fn,
+ gpio_pin_t hint,
+ int* error_out)
+{
+ int i = 0;
+ gpio_pin_opts_t opts;
+ struct gpio_afn_and_pin afn_and_pin[5];
+
+ if (gpio_pin_out_of_range(hint) && hint != -1) {
+ *error_out = GPIO_ERROR_INVALID_PIN;
+ return (gpio_reserved_pin_t) { .v_ = -1 };
+ }
+
+ opts.mode = GPIO_MODE_ALTERNATE;
+
+ if (fn == GPIO_ALTERNATE_FUNCTION_EVENTOUT) {
+ afn_and_pin[i].afn_number = GPIO_ALTERNATE_FUNCTION_EVENTOUT;
+ if (hint == -1) {
+ hint = GPIO_PIN_PA0;
+ }
+ afn_and_pin[i].gpio_pin = hint;
+ } else {
+ get_ports_and_pins_for_alternate_function(fn, afn_and_pin);
+
+ if (hint == -1) {
+ hint = afn_and_pin[0].gpio_pin;
+ }
+
+ for(i = 0;
+ i < 5
+ && afn_and_pin[i].gpio_pin != hint
+ && afn_and_pin[i].gpio_pin != -1;
+ ++ i);
+
+ if (afn_and_pin[i].gpio_pin == -1 || i == 5) {
+ *error_out = GPIO_ERROR_INVALID_PIN_FOR_ALTERNATE_FUNCTION;
+ return (gpio_reserved_pin_t) { .v_ = -1 };
+ }
+ }
+
+ opts.alternate_opts.function = afn_and_pin[i].afn_number;
+ return reserve_gpio_pin(afn_and_pin[i].gpio_pin, &opts, error_out);
+}
+
+void release_gpio_pin(gpio_reserved_pin_t rpin)
+{
+ gpio_pin_t pin = rpin.v_;
+ // TODO this should be a critical section.
+ gpio_port_t port = get_port_for_pin(pin);
+ pins_inuse[pin / 32] &= ~(1 << (pin % 32));
+
+ int used;
+ switch(port) {
+ case GPIO_PORT_A:
+ used = gc_port_a();
+ break;
+ case GPIO_PORT_B:
+ used = gc_port_b();
+ break;
+ case GPIO_PORT_C:
+ used = gc_port_c();
+ break;
+ case GPIO_PORT_D:
+ used = gc_port_d();
+ break;
+ case GPIO_PORT_E:
+ used = gc_port_e();
+ break;
+ case GPIO_PORT_F:
+ used = gc_port_f();
+ break;
+ case GPIO_PORT_G:
+ used = gc_port_g();
+ break;
+ case GPIO_PORT_H:
+ used = gc_port_h();
+ break;
+ case GPIO_PORT_I:
+ used = gc_port_i();
+ break;
+
+ case N_GPIO_PORTS:
+ used = 1;
+ break;
+ }
+
+ if (!used) {
+ regset(RCC.ahb2en_r, rcc_gpioen(port), 0);
+ }
+}
+
+inline void get_gpio_pin_port_off(
+ gpio_pin_t pin, gpio_port_config_t** out_cfg, int* out_off)
+{
+ *out_cfg = get_gpio_port_config_for_pin(pin);
+ *out_off = offset_for_gpio_pin(pin);
+}
+
+void set_gpio_pin_high(gpio_reserved_pin_t pin)
+{
+ int off;
+ gpio_port_config_t* portcfg;
+ get_gpio_pin_port_off(pin.v_, &portcfg, &off);
+
+ regset(portcfg->od_r, (1 << off), 1);
+}
+
+void set_gpio_pin_low(gpio_reserved_pin_t pin)
+{
+ int off;
+ gpio_port_config_t* portcfg;
+ get_gpio_pin_port_off(pin.v_, &portcfg, &off);
+
+ regset(portcfg->od_r, (1 << off), 0);
+}
diff --git a/02-usart/src/kern/gpio/sysled.c b/02-usart/src/kern/gpio/sysled.c
new file mode 100644
index 0000000..a728da3
--- /dev/null
+++ b/02-usart/src/kern/gpio/sysled.c
@@ -0,0 +1,14 @@
+#include "kern/gpio/sysled.h"
+
+#define SYSLED GPIO_PIN_PB3
+
+gpio_reserved_pin_t get_sysled()
+{
+ if (gpio_pin_in_use(SYSLED)) {
+ return (gpio_reserved_pin_t) { .v_ = SYSLED };
+ }
+
+ int ec;
+ gpio_pin_opts_t opts = DEFAULT_GPIO_OPTS_OUTPUT;
+ return reserve_gpio_pin(SYSLED, &opts, &ec);
+}
diff --git a/02-usart/src/kern/main.c b/02-usart/src/kern/main.c
index 0e0c89c..32166bc 100644
--- a/02-usart/src/kern/main.c
+++ b/02-usart/src/kern/main.c
@@ -10,24 +10,23 @@
#include "arch/stm32l4xxx/peripherals/irq.h"
#include "kern/dma/dma_manager.h"
+#include "kern/gpio/gpio_manager.h"
+#include "kern/gpio/sysled.h"
#include "kern/delay.h"
#include "kern/mem.h"
-#include "kern/spin.h"
#include "kern/string.h"
/** Overrides the default systick irq handler. */
void on_systick()
{
static int is_on = 0;
-
- __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
- gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
+ gpio_reserved_pin_t sysled = get_sysled();
if (is_on) {
- pin_off(pin3);
+ set_gpio_pin_low(sysled);
} else {
- pin_on(pin3);
+ set_gpio_pin_high(sysled);
}
is_on = ! is_on;
@@ -35,17 +34,26 @@ void on_systick()
void setup_usart2(uint32_t baud_rate)
{
- __IO gpio_port_t* port_a = enable_gpio(GPIO_PORT_A);
enable_hsi(&RCC, true);
+ int ec = 0;
+ gpio_enable_alternate_function(
+ GPIO_ALTERNATE_FUNCTION_USART2_TX, GPIO_PIN_PA2, &ec);
+
+ if (ec) {
+ unhandled_isr(ec & 0xff);
+ }
+
+ gpio_enable_alternate_function(
+ GPIO_ALTERNATE_FUNCTION_USART2_RX, GPIO_PIN_PA15, &ec);
+
+ if (ec) {
+ unhandled_isr(ec & 0xff);
+ }
+
set_usart2_clock_src(&RCC, USART_CLK_SRC_HSI16);
set_usart2_clock_enabled(&RCC, USART_CLK_SRC_HSI16);
- set_gpio_pin_mode(port_a, PIN_2, MODE_ALTERNATE);
- set_gpio_pin_mode(port_a, PIN_15, MODE_ALTERNATE);
- set_gpio_alternate_function(port_a, PIN_2, AFN_7);
- set_gpio_alternate_function(port_a, PIN_15, AFN_3);
-
/* De-assert reset of USART2 */
regset(RCC.apb1rst1_r, rcc_usart2rst, 0);
@@ -96,14 +104,13 @@ int main()
// regset(USART2.ic_r, usart_tccf, 1);
// dma_mem2p_initiate_transfer(dma_chan, thing, strlen(thing));
- __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
- gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
- pin_on(pin3);
+ gpio_reserved_pin_t sysled = get_sysled();
+ set_gpio_pin_high(sysled);
// usart_printf(&USART2, "Start Configuring Countdown!\n");
/* Set the countdown to start from 1,000,0000. */
- SCB.strv_r = 10000000;
+ SCB.strv_r = 1000000;
/* Enable interrupts. */
regset(SCB.stcs_r, scb_tickint, 1);
diff --git a/02-usart/src/kern/spin.c b/02-usart/src/kern/spin.c
deleted file mode 100644
index 7c4f6eb..0000000
--- a/02-usart/src/kern/spin.c
+++ /dev/null
@@ -1,49 +0,0 @@
-#include "kern/spin.h"
-#include "kern/delay.h"
-#include "arch/stm32l4xxx/peripherals/gpio.h"
-
-#define SHORT_DELAY 200000
-#define LONG_DELAY (SHORT_DELAY * 2)
-
-static void flash_bit(
- uint32_t base, gpio_output_pin_t out_pin,
- uint8_t bit /* 0 => 0, non-zero => 1 */)
-{
- pin_on(out_pin);
- if (bit) {
- delay(base * 2);
- } else {
- delay(base);
- }
- pin_off(out_pin);
- delay(base);
-}
-
-void spin(uint32_t base, uint8_t c)
-{
- uint8_t code;
- __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
- gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
-
- for (;;) {
- code = c;
- flash_bit(base, pin3, code & 0x80);
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
-
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
- code <<= 1;
- flash_bit(base, pin3, code & 0x80);
-
- delay(base * 4);
- }
-}