Resolve UART ISR naming issues

- Call NVIC_SetRAM in supervisor/port.c to move NVIC table to RAM, enabling ISR RAM remapping.
- Rename UART ISR to be generic for any UART IRQn.
- Remove background led writes from background.c.

Author: Brandon-Hurst

ports/analog/background.c

@@ -19,19 +19,13 @@ extern const mxc_gpio_cfg_t led_pin[];
 extern const int num_leds;
 
 /** NOTE: ALL "ticks" refer to a 1/1024 s period */
-static int status_led_ticks = 0;
+static int status_ticks = 0;
 
 // This function is where port-specific background
 // tasks should be performed
 // Execute port specific actions during background tick. Only if ticks are enabled.
 void port_background_tick(void) {
-    status_led_ticks++;
-
-    // Set an LED approx. 1/s
-    if (status_led_ticks > 1024) {
-        MXC_GPIO_OutToggle(led_pin[2].port, led_pin[2].mask);
-        status_led_ticks = 0;
-    }
+    status_ticks++;
 }
 
 // Execute port specific actions during background tasks. This is before the

ports/analog/common-hal/busio/UART.c

@@ -146,7 +146,7 @@ static mxc_uart_parity_t convertParity(busio_uart_parity_t busio_parity) {
     }
 }
 
-void UART0_IRQHandler(void) {
+void uart_isr(void) {
     for (int i = 0; i < NUM_UARTS; i++) {
         if (uarts_active & (1 << i)) {
             MXC_UART_AsyncHandler(MXC_UART_GET_UART(i));
@@ -237,6 +237,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     self->error = E_NO_ERROR;
 
     // Initialize ringbuffer for receiving data
+    // FIXME: Either the use the ringbuf or get rid of it!
     if (self->rx_pin) {
         // if given a ringbuff, use that
         if (receiver_buffer) {
@@ -253,12 +254,18 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     // Indicate to this module that the UART is active
     uarts_active |= (1 << self->uart_id);
 
+    // Set the timeout to a default value
+    if (((timeout < 0.0) || (timeout > 100.0))) {
+        self->timeout = 1.0;
+    } else {
+        self->timeout = timeout;
+    }
 
     /* Setup UART interrupt */
     NVIC_ClearPendingIRQ(MXC_UART_GET_IRQ(self->uart_id));
     NVIC_DisableIRQ(MXC_UART_GET_IRQ(self->uart_id));
     NVIC_SetPriority(MXC_UART_GET_IRQ(self->uart_id), UART_PRIORITY);
-    NVIC_SetVector(MXC_UART_GET_IRQ(self->uart_id), (uint32_t)&UART0_IRQHandler);
+    NVIC_SetVector(MXC_UART_GET_IRQ(self->uart_id), (uint32_t)uart_isr);
 
     return;
 }

ports/analog/supervisor/port.c

@@ -39,6 +39,7 @@
 
 // Sys includes
 #include "max32_port.h"
+#include "nvic_table.h"
 
 // Timers
 #include "mxc_delay.h"
@@ -75,6 +76,13 @@ void SysTick_Handler(void) {
 safe_mode_t port_init(void) {
     int err = E_NO_ERROR;
 
+    // Set Vector Table to RAM & configure ARM core to use RAM-based ISRs
+    // This allows definition of ISRs with custom names
+    //
+    // Useful for mapping ISRs with names not related to a specific IRQn.
+    // Source: https://arm-software.github.io/CMSIS_5/Core/html/using_VTOR_pg.html
+    NVIC_SetRAM();
+
     // 1ms tick timer
     SysTick_Config(SystemCoreClock / 1000);
     NVIC_EnableIRQ(SysTick_IRQn);