machine/nrf: implement i2c.SetBaudRate()

Signed-off-by: deadprogram <[email protected]>

src/machine/machine_nrf.go

@@ -246,11 +246,36 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 	i2c.setPins(config.SCL, config.SDA)
 
 	i2c.mode = config.Mode
+	if i2c.mode == I2CModeController {
+		i2c.SetBaudRate(config.Frequency)
+
+		i2c.enableAsController()
+	} else {
+		i2c.enableAsTarget()
+	}
+
 	i2c.Bus.ENABLE.Set(nrf.TWI_ENABLE_ENABLE_Enabled)
 
 	return nil
 }
 
+// SetBaudRate sets the I2C frequency. It has the side effect of also
+// enabling the I2C hardware if disabled beforehand.
+//
+//go:inline
+func (i2c *I2C) SetBaudRate(br uint32) error {
+	switch {
+	case br >= 400*KHz:
+		i2c.Bus.SetFREQUENCY(nrf.TWI_FREQUENCY_FREQUENCY_K400)
+	case br >= 250*KHz:
+		i2c.Bus.SetFREQUENCY(nrf.TWI_FREQUENCY_FREQUENCY_K250)
+	default:
+		i2c.Bus.SetFREQUENCY(nrf.TWI_FREQUENCY_FREQUENCY_K100)
+	}
+
+	return nil
+}
+
 // signalStop sends a stop signal to the I2C peripheral and waits for confirmation.
 func (i2c *I2C) signalStop() error {
 	tries := 0

src/machine/machine_nrf5x.go

@@ -31,15 +31,6 @@ func (i2c *I2C) disable() {
 	i2c.Bus.ENABLE.Set(0)
 }
 
-// SetBaudRate sets the I2C frequency. It has the side effect of also
-// enabling the I2C hardware if disabled beforehand.
-//
-//go:inline
-func (i2c *I2C) SetBaudRate(br uint32) error {
-	// TODO: implement
-	return nil
-}
-
 // Tx does a single I2C transaction at the specified address.
 // It clocks out the given address, writes the bytes in w, reads back len(r)
 // bytes and stores them in r, and generates a stop condition on the bus.