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Merged
merged 2 commits into from
Dec 22, 2020
Merged

nrf: use SPIM peripheral instead of the legacy SPI peripheral #1517

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20bf0f0
nrf: refactor code a bit to reduce duplication
aykevl Dec 12, 2020
e3e6ee1
nrf: use SPIM peripheral instead of the legacy SPI peripheral
aykevl Dec 1, 2020
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160 changes: 0 additions & 160 deletions src/machine/machine_nrf.go
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Original file line number Diff line number Diff line change
Expand Up @@ -328,163 +328,3 @@ func (i2c I2C) readByte() (byte, error) {
i2c.Bus.EVENTS_RXDREADY.Set(0)
return byte(i2c.Bus.RXD.Get()), nil
}

// SPI on the NRF.
type SPI struct {
Bus *nrf.SPI_Type
}

// There are 2 SPI interfaces on the NRF5x.
var (
SPI0 = SPI{Bus: nrf.SPI0}
SPI1 = SPI{Bus: nrf.SPI1}
)

// 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.SPI_ENABLE_ENABLE_Disabled)

// set frequency
var freq uint32

if config.Frequency == 0 {
config.Frequency = 4000000 // 4MHz
}

switch {
case config.Frequency >= 8000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M8
case config.Frequency >= 4000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M4
case config.Frequency >= 2000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M2
case config.Frequency >= 1000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M1
case config.Frequency >= 500000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_K500
case config.Frequency >= 250000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_K250
default: // below 250kHz, default to the lowest speed available
freq = nrf.SPI_FREQUENCY_FREQUENCY_K125
}
spi.Bus.FREQUENCY.Set(freq)

var conf uint32

// set bit transfer order
if config.LSBFirst {
conf = (nrf.SPI_CONFIG_ORDER_LsbFirst << nrf.SPI_CONFIG_ORDER_Pos)
}

// set mode
switch config.Mode {
case 0:
conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
case 1:
conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
case 2:
conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
case 3:
conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
default: // to mode
conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
}
spi.Bus.CONFIG.Set(conf)

// set pins
spi.setPins(config.SCK, config.SDO, config.SDI)

// Re-enable bus now that it is configured.
spi.Bus.ENABLE.Set(nrf.SPI_ENABLE_ENABLE_Enabled)
}

// Transfer writes/reads a single byte using the SPI interface.
func (spi SPI) Transfer(w byte) (byte, error) {
spi.Bus.TXD.Set(uint32(w))
for spi.Bus.EVENTS_READY.Get() == 0 {
}
r := spi.Bus.RXD.Get()
spi.Bus.EVENTS_READY.Set(0)

// TODO: handle SPI errors
return byte(r), nil
}

// 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
}
173 changes: 162 additions & 11 deletions src/machine/machine_nrf51.go
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Original file line number Diff line number Diff line change
Expand Up @@ -29,18 +29,169 @@ func (i2c I2C) setPins(scl, sda Pin) {
i2c.Bus.PSELSDA.Set(uint32(sda))
}

// 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.SPI_Type
}

// There are 2 SPI interfaces on the NRF51.
var (
SPI0 = SPI{Bus: nrf.SPI0}
SPI1 = SPI{Bus: nrf.SPI1}
)

// 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.SPI_ENABLE_ENABLE_Disabled)

// set frequency
var freq uint32

if config.Frequency == 0 {
config.Frequency = 4000000 // 4MHz
}

switch {
case config.Frequency >= 8000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M8
case config.Frequency >= 4000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M4
case config.Frequency >= 2000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M2
case config.Frequency >= 1000000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_M1
case config.Frequency >= 500000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_K500
case config.Frequency >= 250000:
freq = nrf.SPI_FREQUENCY_FREQUENCY_K250
default: // below 250kHz, default to the lowest speed available
freq = nrf.SPI_FREQUENCY_FREQUENCY_K125
}
spi.Bus.FREQUENCY.Set(freq)

var conf uint32

// set bit transfer order
if config.LSBFirst {
conf = (nrf.SPI_CONFIG_ORDER_LsbFirst << nrf.SPI_CONFIG_ORDER_Pos)
}
if sdo == 0 {
sdo = SPI0_SDO_PIN

// set mode
switch config.Mode {
case 0:
conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
case 1:
conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
case 2:
conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_CONFIG_CPHA_Pos)
case 3:
conf |= (nrf.SPI_CONFIG_CPOL_ActiveLow << nrf.SPI_CONFIG_CPOL_Pos)
conf |= (nrf.SPI_CONFIG_CPHA_Trailing << nrf.SPI_CONFIG_CPHA_Pos)
default: // to mode
conf &^= (nrf.SPI_CONFIG_CPOL_ActiveHigh << nrf.SPI_CONFIG_CPOL_Pos)
conf &^= (nrf.SPI_CONFIG_CPHA_Leading << nrf.SPI_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.PSELSCK.Set(uint32(config.SCK))
spi.Bus.PSELMOSI.Set(uint32(config.SDO))
spi.Bus.PSELMISO.Set(uint32(config.SDI))

// Re-enable bus now that it is configured.
spi.Bus.ENABLE.Set(nrf.SPI_ENABLE_ENABLE_Enabled)
}

// Transfer writes/reads a single byte using the SPI interface.
func (spi SPI) Transfer(w byte) (byte, error) {
spi.Bus.TXD.Set(uint32(w))
for spi.Bus.EVENTS_READY.Get() == 0 {
}
if sdi == 0 {
sdi = SPI0_SDI_PIN
r := spi.Bus.RXD.Get()
spi.Bus.EVENTS_READY.Set(0)

// TODO: handle SPI errors
return byte(r), nil
}

// 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
}
}
}
spi.Bus.PSELSCK.Set(uint32(sck))
spi.Bus.PSELMOSI.Set(uint32(sdo))
spi.Bus.PSELMISO.Set(uint32(sdi))

return nil
}
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