stmhal: Overhaul UART class to use read/write, and improve it.

UART object now uses a stream-like interface: read, readall, readline,
readinto, readchar, write, writechar.

Timeouts are configured when the UART object is initialised, using
timeout and timeout_char keyword args.

The object includes optional read buffering, using interrupts.  You can set
the buffer size dynamically using read_buf_len keyword arg.  A size of 0
disables buffering.

Author: dpgeorge

stmhal/main.c

@@ -320,6 +320,7 @@ int main(void) {
     pin_init0();
     extint_init0();
     timer_init0();
+    uart_init0();
 
 #if MICROPY_HW_ENABLE_RNG
     rng_init0();
@@ -543,6 +544,7 @@ int main(void) {
 
     printf("PYB: soft reboot\n");
     timer_deinit();
+    uart_deinit();
 
     first_soft_reset = false;
     goto soft_reset;

stmhal/qstrdefsport.h

@@ -143,11 +143,17 @@ Q(baudrate)
 Q(bits)
 Q(stop)
 Q(parity)
+Q(read_buf_len)
+Q(buf)
+Q(len)
+Q(timeout)
+Q(timeout_char)
 Q(init)
 Q(deinit)
-Q(all)
-Q(send)
-Q(recv)
+Q(any)
+Q(writechar)
+Q(readchar)
+Q(readinto)
 
 // for CAN class
 Q(CAN)

stmhal/stm32f4xx_it.c

@@ -76,6 +76,7 @@
 #include "obj.h"
 #include "extint.h"
 #include "timer.h"
+#include "uart.h"
 #include "storage.h"
 
 extern void __fatal_error(const char*);
@@ -395,3 +396,24 @@ void TIM8_UP_TIM13_IRQHandler(void) {
 void TIM8_TRG_COM_TIM14_IRQHandler(void) {
     timer_irq_handler(14);
 }
+
+// UART/USART IRQ handlers
+void USART1_IRQHandler(void) {
+    uart_irq_handler(1);
+}
+
+void USART2_IRQHandler(void) {
+    uart_irq_handler(2);
+}
+
+void USART3_IRQHandler(void) {
+    uart_irq_handler(3);
+}
+
+void UART4_IRQHandler(void) {
+    uart_irq_handler(4);
+}
+
+void USART6_IRQHandler(void) {
+    uart_irq_handler(6);
+}