machine/atsamd21: implements UART0 using the SERCOM0 interface
Signed-off-by: Ron Evans <ron@hybridgroup.com>
Этот коммит содержится в:
Ron Evans
Ayke van Laethem
родитель
683e2a66e1
коммит
65ea74bd84
3 изменённых файлов: 135 добавлений и 8 удалений
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@ -8,6 +8,7 @@
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package machine
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import (
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"device/arm"
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"device/sam"
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)
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@ -54,7 +55,7 @@ func (p GPIO) Configure(config GPIOConfig) {
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p.setPMux(val | (GPIO_SERCOM << sam.PORT_PMUX0_PMUXE_Pos))
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}
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// enable port config
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p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR)
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p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR | sam.PORT_PINCFG0_INEN)
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}
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}
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@ -294,3 +295,115 @@ func (p GPIO) setPinCfg(val sam.RegValue8) {
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sam.PORT.PINCFG0_31 = val
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}
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}
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// UART
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var (
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// The first hardware serial port on the SAMD21. Uses the SERCOM0 interface.
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UART0 = &UART{}
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)
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const (
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sampleRate16X = 16
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lsbFirst = 1
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sercomRXPad0 = 0
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sercomRXPad1 = 1
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sercomRXPad2 = 2
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sercomRXPad3 = 3
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sercomTXPad0 = 0 // Only for UART
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sercomTXPad2 = 1 // Only for UART
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sercomTXPad023 = 2 // Only for UART with TX on PAD0, RTS on PAD2 and CTS on PAD3
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)
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// Configure the UART.
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func (uart UART) Configure(config UARTConfig) {
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// Default baud rate to 115200.
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if config.BaudRate == 0 {
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config.BaudRate = 115200
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}
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// enable pins
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GPIO{UART_TX_PIN}.Configure(GPIOConfig{Mode: GPIO_SERCOM})
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GPIO{UART_RX_PIN}.Configure(GPIOConfig{Mode: GPIO_SERCOM})
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// reset SERCOM0
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sam.SERCOM0_USART.CTRLA |= sam.SERCOM_USART_CTRLA_SWRST
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for (sam.SERCOM0_USART.CTRLA&sam.SERCOM_USART_CTRLA_SWRST) > 0 ||
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(sam.SERCOM0_USART.SYNCBUSY&sam.SERCOM_USART_SYNCBUSY_SWRST) > 0 {
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}
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// set UART mode/sample rate
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// SERCOM_USART_CTRLA_MODE(mode) |
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// SERCOM_USART_CTRLA_SAMPR(sampleRate);
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sam.SERCOM0_USART.CTRLA = (sam.SERCOM_USART_CTRLA_MODE_USART_INT_CLK << sam.SERCOM_USART_CTRLA_MODE_Pos) |
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(1 << sam.SERCOM_USART_CTRLA_SAMPR_Pos) // sample rate of 16x
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// Set baud rate
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uart.SetBaudRate(config.BaudRate)
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// setup UART frame
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// SERCOM_USART_CTRLA_FORM( (parityMode == SERCOM_NO_PARITY ? 0 : 1) ) |
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// dataOrder << SERCOM_USART_CTRLA_DORD_Pos;
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sam.SERCOM0_USART.CTRLA |= (0 << sam.SERCOM_USART_CTRLA_FORM_Pos) | // no parity
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(lsbFirst << sam.SERCOM_USART_CTRLA_DORD_Pos) // data order
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// set UART stop bits/parity
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// SERCOM_USART_CTRLB_CHSIZE(charSize) |
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// nbStopBits << SERCOM_USART_CTRLB_SBMODE_Pos |
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// (parityMode == SERCOM_NO_PARITY ? 0 : parityMode) << SERCOM_USART_CTRLB_PMODE_Pos; //If no parity use default value
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sam.SERCOM0_USART.CTRLB |= (0 << sam.SERCOM_USART_CTRLB_CHSIZE_Pos) | // 8 bits is 0
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(0 << sam.SERCOM_USART_CTRLB_SBMODE_Pos) | // 1 stop bit is zero
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(0 << sam.SERCOM_USART_CTRLB_PMODE_Pos) // no parity
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// set UART pads. This is not same as pins...
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// SERCOM_USART_CTRLA_TXPO(txPad) |
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// SERCOM_USART_CTRLA_RXPO(rxPad);
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sam.SERCOM0_USART.CTRLA |= (sercomTXPad2 << sam.SERCOM_USART_CTRLA_TXPO_Pos) |
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(sercomRXPad3 << sam.SERCOM_USART_CTRLA_RXPO_Pos)
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// Enable Transceiver and Receiver
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//sercom->USART.CTRLB.reg |= SERCOM_USART_CTRLB_TXEN | SERCOM_USART_CTRLB_RXEN ;
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sam.SERCOM0_USART.CTRLB |= (sam.SERCOM_USART_CTRLB_TXEN | sam.SERCOM_USART_CTRLB_RXEN)
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// Enable USART1 port.
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// sercom->USART.CTRLA.bit.ENABLE = 0x1u;
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sam.SERCOM0_USART.CTRLA |= sam.SERCOM_USART_CTRLA_ENABLE
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for (sam.SERCOM0_USART.SYNCBUSY & sam.SERCOM_USART_SYNCBUSY_ENABLE) > 0 {
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}
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// setup interrupt on receive
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sam.SERCOM0_USART.INTENSET = sam.SERCOM_USART_INTENSET_RXC
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// Enable RX IRQ.
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//arm.SetPriority(sam.IRQ_SERCOM0, 0xc0)
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arm.EnableIRQ(sam.IRQ_SERCOM0)
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}
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// SetBaudRate sets the communication speed for the UART.
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func (uart UART) SetBaudRate(br uint32) {
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// Asynchronous fractional mode (Table 24-2 in datasheet)
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// BAUD = fref / (sampleRateValue * fbaud)
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// (multiply by 8, to calculate fractional piece)
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// uint32_t baudTimes8 = (SystemCoreClock * 8) / (16 * baudrate);
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baud := (CPU_FREQUENCY * 8) / (sampleRate16X * br)
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// sercom->USART.BAUD.FRAC.FP = (baudTimes8 % 8);
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// sercom->USART.BAUD.FRAC.BAUD = (baudTimes8 / 8);
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sam.SERCOM0_USART.BAUD = sam.RegValue16(((baud % 8) << sam.SERCOM_USART_BAUD_FRAC_MODE_FP_Pos) |
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((baud / 8) << sam.SERCOM_USART_BAUD_FRAC_MODE_BAUD_Pos))
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}
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// WriteByte writes a byte of data to the UART.
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func (uart UART) WriteByte(c byte) error {
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// wait until ready to receive
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for (sam.SERCOM0_USART.INTFLAG & sam.SERCOM_USART_INTFLAG_DRE) == 0 {
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}
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sam.SERCOM0_USART.DATA = sam.RegValue16(c)
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return nil
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}
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//go:export SERCOM0_IRQHandler
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func handleUART0() {
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// should reset IRQ
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bufferPut(byte((sam.SERCOM0_USART.DATA & 0xFF)))
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sam.SERCOM0_USART.INTFLAG |= sam.SERCOM_USART_INTFLAG_RXC
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}
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@ -1,4 +1,4 @@
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// +build avr nrf stm32
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// +build avr nrf sam stm32
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package machine
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@ -5,6 +5,7 @@ package runtime
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import (
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"device/arm"
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"device/sam"
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"machine"
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"unsafe"
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)
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@ -21,16 +22,14 @@ func main() {
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func init() {
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initClocks()
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initRTC()
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initUARTClock()
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// Turn on clock to SERCOM0 for Serial
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sam.PM.APBCMASK |= sam.PM_APBCMASK_SERCOM0_
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// TODO: connect to UART
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// connect to UART
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machine.UART0.Configure(machine.UARTConfig{})
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}
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func putchar(c byte) {
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// TODO: write byte to UART
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//machine.UART0.WriteByte(c)
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machine.UART0.WriteByte(c)
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}
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func initClocks() {
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@ -216,6 +215,7 @@ func initRTC() {
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sam.RTC_MODE0.CTRL |= sam.RTC_MODE0_CTRL_ENABLE
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waitForSync()
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arm.SetPriority(sam.IRQ_RTC, 0xc0)
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arm.EnableIRQ(sam.IRQ_RTC)
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}
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@ -292,3 +292,17 @@ func handleRTC() {
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timerWakeup = true
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}
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func initUARTClock() {
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// Turn on clock to SERCOM0 for Serial
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sam.PM.APBCMASK |= sam.PM_APBCMASK_SERCOM0_
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// Use GCLK0 for SERCOM0 aka UART0
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// GCLK_CLKCTRL_ID( clockId ) | // Generic Clock 0 (SERCOMx)
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// GCLK_CLKCTRL_GEN_GCLK0 | // Generic Clock Generator 0 is source
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// GCLK_CLKCTRL_CLKEN ;
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sam.GCLK.CLKCTRL = sam.RegValue16((sam.GCLK_CLKCTRL_ID_SERCOM0_CORE << sam.GCLK_CLKCTRL_ID_Pos) |
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(sam.GCLK_CLKCTRL_GEN_GCLK0 << sam.GCLK_CLKCTRL_GEN_Pos) |
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sam.GCLK_CLKCTRL_CLKEN)
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waitForSync()
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}
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