nrf: use SPIM peripheral instead of the legacy SPI peripheral
This newer peripheral supports DMA (through EasyDMA) and should generally be faster. Importantly for some operations: interrupts (within 255 byte buffers) will not interfere with the SPI transfer.
Этот коммит содержится в:
Ayke van Laethem
Ron Evans
родитель
ce539ce583
коммит
cda5fffd98
3 изменённых файлов: 305 добавлений и 185 удалений
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@ -328,163 +328,3 @@ func (i2c I2C) readByte() (byte, error) {
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i2c.Bus.EVENTS_RXDREADY.Set(0)
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return byte(i2c.Bus.RXD.Get()), nil
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}
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// SPI on the NRF.
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type SPI struct {
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Bus *nrf.SPI_Type
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}
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// There are 2 SPI interfaces on the NRF5x.
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var (
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SPI0 = SPI{Bus: nrf.SPI0}
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SPI1 = SPI{Bus: nrf.SPI1}
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)
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// SPIConfig is used to store config info for SPI.
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type SPIConfig struct {
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Frequency uint32
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SCK Pin
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SDO Pin
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SDI Pin
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LSBFirst bool
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Mode uint8
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}
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// Configure is intended to setup the SPI interface.
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func (spi SPI) Configure(config SPIConfig) {
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// Disable bus to configure it
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spi.Bus.ENABLE.Set(nrf.SPI_ENABLE_ENABLE_Disabled)
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// set frequency
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var freq uint32
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if config.Frequency == 0 {
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config.Frequency = 4000000 // 4MHz
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}
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switch {
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case config.Frequency >= 8000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M8
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case config.Frequency >= 4000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M4
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case config.Frequency >= 2000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M2
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case config.Frequency >= 1000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M1
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case config.Frequency >= 500000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_K500
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case config.Frequency >= 250000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_K250
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default: // below 250kHz, default to the lowest speed available
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freq = nrf.SPI_FREQUENCY_FREQUENCY_K125
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}
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spi.Bus.FREQUENCY.Set(freq)
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var conf uint32
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// set bit transfer order
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if config.LSBFirst {
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conf = (nrf.SPI_CONFIG_ORDER_LsbFirst << nrf.SPI_CONFIG_ORDER_Pos)
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}
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// set mode
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switch config.Mode {
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case 0:
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conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
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conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
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case 1:
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conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
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conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
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case 2:
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conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
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conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
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case 3:
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conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
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conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
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default: // to mode
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conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
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conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
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}
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spi.Bus.CONFIG.Set(conf)
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// set pins
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spi.setPins(config.SCK, config.SDO, config.SDI)
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// Re-enable bus now that it is configured.
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spi.Bus.ENABLE.Set(nrf.SPI_ENABLE_ENABLE_Enabled)
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}
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// Transfer writes/reads a single byte using the SPI interface.
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func (spi SPI) Transfer(w byte) (byte, error) {
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spi.Bus.TXD.Set(uint32(w))
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for spi.Bus.EVENTS_READY.Get() == 0 {
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}
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r := spi.Bus.RXD.Get()
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spi.Bus.EVENTS_READY.Set(0)
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// TODO: handle SPI errors
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return byte(r), nil
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}
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// Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
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// interface, there must always be the same number of bytes written as bytes read.
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// The Tx method knows about this, and offers a few different ways of calling it.
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//
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// This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.
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// Note that the tx and rx buffers must be the same size:
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//
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// spi.Tx(tx, rx)
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//
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// This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros
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// until all the bytes in the command packet have been received:
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//
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// spi.Tx(tx, nil)
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//
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// This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":
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//
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// spi.Tx(nil, rx)
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//
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func (spi SPI) Tx(w, r []byte) error {
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var err error
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switch {
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case len(w) == 0:
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// read only, so write zero and read a result.
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for i := range r {
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r[i], err = spi.Transfer(0)
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if err != nil {
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return err
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}
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}
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case len(r) == 0:
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// write only
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spi.Bus.TXD.Set(uint32(w[0]))
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w = w[1:]
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for _, b := range w {
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spi.Bus.TXD.Set(uint32(b))
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for spi.Bus.EVENTS_READY.Get() == 0 {
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}
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spi.Bus.EVENTS_READY.Set(0)
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_ = spi.Bus.RXD.Get()
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}
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for spi.Bus.EVENTS_READY.Get() == 0 {
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}
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spi.Bus.EVENTS_READY.Set(0)
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_ = spi.Bus.RXD.Get()
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default:
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// write/read
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if len(w) != len(r) {
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return ErrTxInvalidSliceSize
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}
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for i, b := range w {
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r[i], err = spi.Transfer(b)
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if err != nil {
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return err
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}
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}
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}
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return nil
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}
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@ -29,18 +29,169 @@ func (i2c I2C) setPins(scl, sda Pin) {
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i2c.Bus.PSELSDA.Set(uint32(sda))
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}
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// SPI
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func (spi SPI) setPins(sck, sdo, sdi Pin) {
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if sck == 0 {
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sck = SPI0_SCK_PIN
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}
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if sdo == 0 {
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sdo = SPI0_SDO_PIN
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}
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if sdi == 0 {
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sdi = SPI0_SDI_PIN
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}
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spi.Bus.PSELSCK.Set(uint32(sck))
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spi.Bus.PSELMOSI.Set(uint32(sdo))
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spi.Bus.PSELMISO.Set(uint32(sdi))
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// SPI on the NRF.
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type SPI struct {
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Bus *nrf.SPI_Type
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}
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// There are 2 SPI interfaces on the NRF51.
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var (
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SPI0 = SPI{Bus: nrf.SPI0}
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SPI1 = SPI{Bus: nrf.SPI1}
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)
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// SPIConfig is used to store config info for SPI.
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type SPIConfig struct {
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Frequency uint32
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SCK Pin
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SDO Pin
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SDI Pin
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LSBFirst bool
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Mode uint8
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}
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// Configure is intended to setup the SPI interface.
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func (spi SPI) Configure(config SPIConfig) {
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// Disable bus to configure it
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spi.Bus.ENABLE.Set(nrf.SPI_ENABLE_ENABLE_Disabled)
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// set frequency
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var freq uint32
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if config.Frequency == 0 {
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config.Frequency = 4000000 // 4MHz
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}
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switch {
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case config.Frequency >= 8000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M8
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case config.Frequency >= 4000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M4
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case config.Frequency >= 2000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M2
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case config.Frequency >= 1000000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_M1
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case config.Frequency >= 500000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_K500
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case config.Frequency >= 250000:
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freq = nrf.SPI_FREQUENCY_FREQUENCY_K250
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default: // below 250kHz, default to the lowest speed available
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freq = nrf.SPI_FREQUENCY_FREQUENCY_K125
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}
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spi.Bus.FREQUENCY.Set(freq)
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var conf uint32
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// set bit transfer order
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if config.LSBFirst {
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conf = (nrf.SPI_CONFIG_ORDER_LsbFirst << nrf.SPI_CONFIG_ORDER_Pos)
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}
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// set mode
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switch config.Mode {
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case 0:
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conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
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conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
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case 1:
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conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
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conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
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case 2:
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conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
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conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
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case 3:
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conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
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conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
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default: // to mode
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conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
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conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
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}
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spi.Bus.CONFIG.Set(conf)
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// set pins
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if config.SCK == 0 && config.SDO == 0 && config.SDI == 0 {
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config.SCK = SPI0_SCK_PIN
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config.SDO = SPI0_SDO_PIN
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config.SDI = SPI0_SDI_PIN
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}
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spi.Bus.PSELSCK.Set(uint32(config.SCK))
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spi.Bus.PSELMOSI.Set(uint32(config.SDO))
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spi.Bus.PSELMISO.Set(uint32(config.SDI))
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// Re-enable bus now that it is configured.
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spi.Bus.ENABLE.Set(nrf.SPI_ENABLE_ENABLE_Enabled)
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}
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// Transfer writes/reads a single byte using the SPI interface.
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func (spi SPI) Transfer(w byte) (byte, error) {
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spi.Bus.TXD.Set(uint32(w))
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for spi.Bus.EVENTS_READY.Get() == 0 {
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}
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r := spi.Bus.RXD.Get()
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spi.Bus.EVENTS_READY.Set(0)
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// TODO: handle SPI errors
|
||||
return byte(r), nil
|
||||
}
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|
||||
// Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
|
||||
// interface, there must always be the same number of bytes written as bytes read.
|
||||
// The Tx method knows about this, and offers a few different ways of calling it.
|
||||
//
|
||||
// This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.
|
||||
// Note that the tx and rx buffers must be the same size:
|
||||
//
|
||||
// spi.Tx(tx, rx)
|
||||
//
|
||||
// This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros
|
||||
// until all the bytes in the command packet have been received:
|
||||
//
|
||||
// spi.Tx(tx, nil)
|
||||
//
|
||||
// This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":
|
||||
//
|
||||
// spi.Tx(nil, rx)
|
||||
//
|
||||
func (spi SPI) Tx(w, r []byte) error {
|
||||
var err error
|
||||
|
||||
switch {
|
||||
case len(w) == 0:
|
||||
// read only, so write zero and read a result.
|
||||
for i := range r {
|
||||
r[i], err = spi.Transfer(0)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
}
|
||||
case len(r) == 0:
|
||||
// write only
|
||||
spi.Bus.TXD.Set(uint32(w[0]))
|
||||
w = w[1:]
|
||||
for _, b := range w {
|
||||
spi.Bus.TXD.Set(uint32(b))
|
||||
for spi.Bus.EVENTS_READY.Get() == 0 {
|
||||
}
|
||||
spi.Bus.EVENTS_READY.Set(0)
|
||||
_ = spi.Bus.RXD.Get()
|
||||
}
|
||||
for spi.Bus.EVENTS_READY.Get() == 0 {
|
||||
}
|
||||
spi.Bus.EVENTS_READY.Set(0)
|
||||
_ = spi.Bus.RXD.Get()
|
||||
|
||||
default:
|
||||
// write/read
|
||||
if len(w) != len(r) {
|
||||
return ErrTxInvalidSliceSize
|
||||
}
|
||||
|
||||
for i, b := range w {
|
||||
r[i], err = spi.Transfer(b)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return nil
|
||||
}
|
||||
|
|
|
|||
|
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@ -111,20 +111,149 @@ func (a ADC) Get() uint16 {
|
|||
return uint16(value << 4)
|
||||
}
|
||||
|
||||
// SPI
|
||||
func (spi SPI) setPins(sck, sdo, sdi Pin) {
|
||||
if sck == 0 {
|
||||
sck = SPI0_SCK_PIN
|
||||
// SPI on the NRF.
|
||||
type SPI struct {
|
||||
Bus *nrf.SPIM_Type
|
||||
}
|
||||
|
||||
// There are 3 SPI interfaces on the NRF528xx.
|
||||
var (
|
||||
SPI0 = SPI{Bus: nrf.SPIM0}
|
||||
SPI1 = SPI{Bus: nrf.SPIM1}
|
||||
SPI2 = SPI{Bus: nrf.SPIM2}
|
||||
)
|
||||
|
||||
// SPIConfig is used to store config info for SPI.
|
||||
type SPIConfig struct {
|
||||
Frequency uint32
|
||||
SCK Pin
|
||||
SDO Pin
|
||||
SDI Pin
|
||||
LSBFirst bool
|
||||
Mode uint8
|
||||
}
|
||||
|
||||
// Configure is intended to setup the SPI interface.
|
||||
func (spi SPI) Configure(config SPIConfig) {
|
||||
// Disable bus to configure it
|
||||
spi.Bus.ENABLE.Set(nrf.SPIM_ENABLE_ENABLE_Disabled)
|
||||
|
||||
// Pick a default frequency.
|
||||
if config.Frequency == 0 {
|
||||
config.Frequency = 4000000 // 4MHz
|
||||
}
|
||||
if sdo == 0 {
|
||||
sdo = SPI0_SDO_PIN
|
||||
|
||||
// set frequency
|
||||
var freq uint32
|
||||
switch {
|
||||
case config.Frequency >= 8000000:
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_M8
|
||||
case config.Frequency >= 4000000:
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_M4
|
||||
case config.Frequency >= 2000000:
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_M2
|
||||
case config.Frequency >= 1000000:
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_M1
|
||||
case config.Frequency >= 500000:
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_K500
|
||||
case config.Frequency >= 250000:
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_K250
|
||||
default: // below 250kHz, default to the lowest speed available
|
||||
freq = nrf.SPIM_FREQUENCY_FREQUENCY_K125
|
||||
}
|
||||
if sdi == 0 {
|
||||
sdi = SPI0_SDI_PIN
|
||||
spi.Bus.FREQUENCY.Set(freq)
|
||||
|
||||
var conf uint32
|
||||
|
||||
// set bit transfer order
|
||||
if config.LSBFirst {
|
||||
conf = (nrf.SPIM_CONFIG_ORDER_LsbFirst << nrf.SPIM_CONFIG_ORDER_Pos)
|
||||
}
|
||||
spi.Bus.PSEL.SCK.Set(uint32(sck))
|
||||
spi.Bus.PSEL.MOSI.Set(uint32(sdo))
|
||||
spi.Bus.PSEL.MISO.Set(uint32(sdi))
|
||||
|
||||
// set mode
|
||||
switch config.Mode {
|
||||
case 0:
|
||||
conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
|
||||
conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
|
||||
case 1:
|
||||
conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
|
||||
conf |= (nrf.SPIM_CONFIG_CPHA_Trailing << nrf.SPIM_CONFIG_CPHA_Pos)
|
||||
case 2:
|
||||
conf |= (nrf.SPIM_CONFIG_CPOL_ActiveLow << nrf.SPIM_CONFIG_CPOL_Pos)
|
||||
conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
|
||||
case 3:
|
||||
conf |= (nrf.SPIM_CONFIG_CPOL_ActiveLow << nrf.SPIM_CONFIG_CPOL_Pos)
|
||||
conf |= (nrf.SPIM_CONFIG_CPHA_Trailing << nrf.SPIM_CONFIG_CPHA_Pos)
|
||||
default: // to mode
|
||||
conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
|
||||
conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
|
||||
}
|
||||
spi.Bus.CONFIG.Set(conf)
|
||||
|
||||
// set pins
|
||||
if config.SCK == 0 && config.SDO == 0 && config.SDI == 0 {
|
||||
config.SCK = SPI0_SCK_PIN
|
||||
config.SDO = SPI0_SDO_PIN
|
||||
config.SDI = SPI0_SDI_PIN
|
||||
}
|
||||
spi.Bus.PSEL.SCK.Set(uint32(config.SCK))
|
||||
spi.Bus.PSEL.MOSI.Set(uint32(config.SDO))
|
||||
spi.Bus.PSEL.MISO.Set(uint32(config.SDI))
|
||||
|
||||
// Re-enable bus now that it is configured.
|
||||
spi.Bus.ENABLE.Set(nrf.SPIM_ENABLE_ENABLE_Enabled)
|
||||
}
|
||||
|
||||
// Transfer writes/reads a single byte using the SPI interface.
|
||||
func (spi SPI) Transfer(w byte) (byte, error) {
|
||||
var wbuf, rbuf [1]byte
|
||||
wbuf[0] = w
|
||||
err := spi.Tx(wbuf[:], rbuf[:])
|
||||
return rbuf[0], err
|
||||
}
|
||||
|
||||
// Tx handles read/write operation for SPI interface. Since SPI is a syncronous
|
||||
// write/read interface, there must always be the same number of bytes written
|
||||
// as bytes read. Therefore, if the number of bytes don't match it will be
|
||||
// padded until they fit: if len(w) > len(r) the extra bytes received will be
|
||||
// dropped and if len(w) < len(r) extra 0 bytes will be sent.
|
||||
func (spi SPI) Tx(w, r []byte) error {
|
||||
// Unfortunately the hardware (on the nrf52832) only supports up to 255
|
||||
// bytes in the buffers, so if either w or r is longer than that the
|
||||
// transfer needs to be broken up in pieces.
|
||||
// The nrf52840 supports far larger buffers however, which isn't yet
|
||||
// supported.
|
||||
for len(r) != 0 || len(w) != 0 {
|
||||
// Prepare the SPI transfer: set the DMA pointers and lengths.
|
||||
if len(r) != 0 {
|
||||
spi.Bus.RXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&r[0]))))
|
||||
n := uint32(len(r))
|
||||
if n > 255 {
|
||||
n = 255
|
||||
}
|
||||
spi.Bus.RXD.MAXCNT.Set(n)
|
||||
r = r[n:]
|
||||
}
|
||||
if len(w) != 0 {
|
||||
spi.Bus.TXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&w[0]))))
|
||||
n := uint32(len(w))
|
||||
if n > 255 {
|
||||
n = 255
|
||||
}
|
||||
spi.Bus.TXD.MAXCNT.Set(n)
|
||||
w = w[n:]
|
||||
}
|
||||
|
||||
// Do the transfer.
|
||||
// Note: this can be improved by not waiting until the transfer is
|
||||
// finished if the transfer is send-only (a common case).
|
||||
spi.Bus.TASKS_START.Set(1)
|
||||
for spi.Bus.EVENTS_END.Get() == 0 {
|
||||
}
|
||||
spi.Bus.EVENTS_END.Set(0)
|
||||
}
|
||||
|
||||
return nil
|
||||
}
|
||||
|
||||
// InitPWM initializes the registers needed for PWM.
|
||||
|
|
|
|||
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