diff --git a/src/machine/board_bluepill.go b/src/machine/board_bluepill.go
index 7ec73147..39c7d421 100644
--- a/src/machine/board_bluepill.go
+++ b/src/machine/board_bluepill.go
@@ -2,6 +2,8 @@
 
 package machine
 
+import "device/stm32"
+
 // https://wiki.stm32duino.com/index.php?title=File:Bluepillpinout.gif
 const (
 	PA0  = portA + 0
@@ -47,10 +49,28 @@ const (
 
 // UART pins
 const (
-	UART_TX_PIN = PA9
-	UART_RX_PIN = PA10
+	UART_TX_PIN     = PA9
+	UART_RX_PIN     = PA10
+	UART_ALT_TX_PIN = PB6
+	UART_ALT_RX_PIN = PB7
 )
 
+var (
+	// USART1 is the first hardware serial port on the STM32.
+	// Both UART0 and UART1 refer to USART1.
+	UART0 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    stm32.USART1,
+		IRQVal: stm32.IRQ_USART1,
+	}
+	UART1 = &UART0
+)
+
+//go:export USART1_IRQHandler
+func handleUART1() {
+	UART1.Receive(byte((UART1.Bus.DR.Get() & 0xFF)))
+}
+
 // SPI pins
 const (
 	SPI0_SCK_PIN  = PA5
diff --git a/src/machine/machine_stm32f103xx.go b/src/machine/machine_stm32f103xx.go
index 44fa8742..ecded417 100644
--- a/src/machine/machine_stm32f103xx.go
+++ b/src/machine/machine_stm32f103xx.go
@@ -110,15 +110,10 @@ func (p Pin) Get() bool {
 // UART
 type UART struct {
 	Buffer *RingBuffer
+	Bus    *stm32.USART_Type
+	IRQVal uint32
 }
 
-var (
-	// USART1 is the first hardware serial port on the STM32.
-	// Both UART0 and UART1 refer to USART1.
-	UART0 = UART{Buffer: NewRingBuffer()}
-	UART1 = &UART0
-)
-
 // Configure the UART.
 func (uart UART) Configure(config UARTConfig) {
 	// Default baud rate to 115200.
@@ -128,53 +123,63 @@ func (uart UART) Configure(config UARTConfig) {
 
 	// pins
 	switch config.TX {
-	case PB6:
-		// use alternate TX/RX pins PB6/PB7 via AFIO mapping
+	case UART_ALT_TX_PIN:
+		// use alternate TX/RX pins via AFIO mapping
 		stm32.RCC.APB2ENR.SetBits(stm32.RCC_APB2ENR_AFIOEN)
-		stm32.AFIO.MAPR.SetBits(stm32.AFIO_MAPR_USART1_REMAP)
-		PB6.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
-		PB7.Configure(PinConfig{Mode: PinInputModeFloating})
+		if uart.Bus == stm32.USART1 {
+			stm32.AFIO.MAPR.SetBits(stm32.AFIO_MAPR_USART1_REMAP)
+		} else if uart.Bus == stm32.USART2 {
+			stm32.AFIO.MAPR.SetBits(stm32.AFIO_MAPR_USART2_REMAP)
+		}
+		UART_ALT_TX_PIN.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
+		UART_ALT_RX_PIN.Configure(PinConfig{Mode: PinInputModeFloating})
 	default:
 		// use standard TX/RX pins PA9 and PA10
 		UART_TX_PIN.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
 		UART_RX_PIN.Configure(PinConfig{Mode: PinInputModeFloating})
 	}
 
-	// Enable USART1 clock
-	stm32.RCC.APB2ENR.SetBits(stm32.RCC_APB2ENR_USART1EN)
+	// Enable USART clock
+	if uart.Bus == stm32.USART1 {
+		stm32.RCC.APB2ENR.SetBits(stm32.RCC_APB2ENR_USART1EN)
+	} else if uart.Bus == stm32.USART2 {
+		stm32.RCC.APB1ENR.SetBits(stm32.RCC_APB1ENR_USART2EN)
+	}
 
 	// Set baud rate
 	uart.SetBaudRate(config.BaudRate)
 
-	// Enable USART1 port.
-	stm32.USART1.CR1.Set(stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE)
+	// Enable USART port
+	uart.Bus.CR1.Set(stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE)
 
-	// Enable RX IRQ.
-	arm.SetPriority(stm32.IRQ_USART1, 0xc0)
-	arm.EnableIRQ(stm32.IRQ_USART1)
+	// Enable RX IRQ
+	arm.SetPriority(uart.IRQVal, 0xc0)
+	arm.EnableIRQ(uart.IRQVal)
 }
 
 // SetBaudRate sets the communication speed for the UART.
 func (uart UART) SetBaudRate(br uint32) {
-	// first divide by PCLK2 prescaler (div 1) and then desired baudrate
-	divider := CPU_FREQUENCY / br
-	stm32.USART1.BRR.Set(divider)
+	// Note: PCLK2 (from APB2) used for USART1 and PCLK1 for USART2, 3, 4, 5
+	var divider uint32
+	if uart.Bus == stm32.USART1 {
+		// first divide by PCLK2 prescaler (div 1) and then desired baudrate
+		divider = CPU_FREQUENCY / br
+	} else {
+		// first divide by PCLK1 prescaler (div 2) and then desired baudrate
+		divider = CPU_FREQUENCY / 2 / br
+	}
+	uart.Bus.BRR.Set(divider)
 }
 
 // WriteByte writes a byte of data to the UART.
 func (uart UART) WriteByte(c byte) error {
-	stm32.USART1.DR.Set(uint32(c))
+	uart.Bus.DR.Set(uint32(c))
 
-	for !stm32.USART1.SR.HasBits(stm32.USART_SR_TXE) {
+	for !uart.Bus.SR.HasBits(stm32.USART_SR_TXE) {
 	}
 	return nil
 }
 
-//go:export USART1_IRQHandler
-func handleUART1() {
-	UART1.Receive(byte((stm32.USART1.DR.Get() & 0xFF)))
-}
-
 // SPI on the STM32.
 type SPI struct {
 	Bus *stm32.SPI_Type