Better hackrf board detection for the serial info command (#2967)

firmware/application/hackrf_core_mini.c

@@ -0,0 +1,56 @@
+#include "gpio_lpc.h"
+
+typedef enum {
+    LED1 = 0,
+    LED2 = 1,
+    LED3 = 2,
+    LED4 = 3,
+} led_t;
+
+/* GPIO Output PinMux */
+static struct gpio_t gpio_led[] = {
+    GPIO(2, 1),
+    GPIO(2, 2),
+    GPIO(2, 8),
+#ifdef RAD1O
+    GPIO(5, 26),
+#endif
+};
+
+void delay(uint32_t duration) {
+    while (duration--) {
+        /* cannot be optimized out */
+        __asm__ volatile("nop");
+    }
+}
+
+void delay_us_at_mhz(uint32_t us, uint32_t mhz) {
+    /* overflow-safe multiply */
+    uint64_t cycles64 = (uint64_t)us * (uint64_t)mhz;
+    if (cycles64 > UINT32_MAX) {
+        cycles64 = UINT32_MAX;
+    }
+    delay((uint32_t)cycles64);
+}
+
+void led_on(const led_t led) {
+    gpio_set(&gpio_led[led]);
+}
+
+void led_off(const led_t led) {
+    gpio_clear(&gpio_led[led]);
+}
+
+void halt_and_flash(const uint32_t duration) {
+    /* blink LED1, LED2, and LED3 */
+    while (1) {
+        led_on(LED1);
+        led_on(LED2);
+        led_on(LED3);
+        delay(duration);
+        led_off(LED1);
+        led_off(LED2);
+        led_off(LED3);
+        delay(duration);
+    }
+}