machine: implement default UART pin configuration for Embedfire boards

Author: burgrp

src/machine/board_embedfire_py32f002b.go

@@ -18,10 +18,7 @@ const (
 	KEY2 = PA0
 )
 
-// UART
-const (
-	DEFAULT_UART_TX_PIN    = PA6
-	DEFAULT_UART_RX_PIN    = PA7
-	DEFAULT_UART_TX_PIN_AF = 1
-	DEFAULT_UART_RX_PIN_AF = 3
-)
+func configureDefaultUARTPins() {
+	ConfigureUARTPin(PA6, 1) // TX
+	ConfigureUARTPin(PA7, 3) // RX
+}

src/machine/board_embedfire_py32f030.go

@@ -18,10 +18,7 @@ const (
 	KEY2 = PA6
 )
 
-// UART
-const (
-	DEFAULT_UART_TX_PIN    = PA7
-	DEFAULT_UART_RX_PIN    = PA8
-	DEFAULT_UART_TX_PIN_AF = 8
-	DEFAULT_UART_RX_PIN_AF = 8
-)
+func configureDefaultUARTPins() {
+	ConfigureUARTPin(PA7, 8) // TX
+	ConfigureUARTPin(PA8, 8) // RX
+}

src/machine/machine_py32_uart.go

@@ -23,19 +23,11 @@ var DefaultUART = &UART{Bus: py32.USART1, Buffer: NewRingBuffer()}
 // ConfigureWithClock initializes the UART using the provided peripheral clock
 // frequency (in Hz). This avoids assuming a fixed MCU clock.
 func (uart *UART) ConfigureWithClock(config UARTConfig, clockHz uint32) error {
+
 	if config.BaudRate == 0 {
 		config.BaudRate = 115200
 	}
 
-	// Configure default pins if they weren't provided.
-	if config.TX == 0 {
-		ConfigureUARTPin(DEFAULT_UART_TX_PIN, DEFAULT_UART_TX_PIN_AF)
-	}
-
-	if config.RX == 0 {
-		ConfigureUARTPin(DEFAULT_UART_RX_PIN, DEFAULT_UART_RX_PIN_AF)
-	}
-
 	// Enable peripheral clock.
 	py32.RCC.APBENR2.SetBits(py32.RCC_APBENR2_USART1EN)
 
@@ -56,6 +48,8 @@ func (uart *UART) ConfigureWithClock(config UARTConfig, clockHz uint32) error {
 	uart.irq.SetPriority(0xc0)
 	uart.irq.Enable()
 
+	configureDefaultUARTPins()
+
 	return nil
 }
 

src/machine/machine_py32_uart_no_default_pins.go

@@ -0,0 +1,8 @@
+//go:build py32 && !default_uart_pins
+
+package machine
+
+func configureDefaultUARTPins() {
+	// There are no default UART pins for this board. Configure them in
+	// application main() using ConfigureUARTPin().
+}

targets/embedfire-py32f002b.json

@@ -4,6 +4,7 @@
   ],
   "flash-command": "pyocd load -t py32f002bx5 {bin}",
   "build-tags": [
-    "embedfire_py32f002b"
+    "embedfire_py32f002b",
+		"default_uart_pins"
   ]
 }

targets/embedfire-py32f030.json

@@ -4,6 +4,7 @@
 	],
 	"flash-command": "pyocd load -t py32f003x8 {bin}",
 	"build-tags": [
-		"embedfire_py32f030"
+		"embedfire_py32f030",
+		"default_uart_pins"
 	]
 }