diff --git a/rpio.go b/rpio.go index 155766c..50017c6 100644 --- a/rpio.go +++ b/rpio.go @@ -85,6 +85,7 @@ const ( gpioOffset = 0x200000 clkOffset = 0x101000 pwmOffset = 0x20C000 + spiOffset = 0x204000 memLength = 4096 ) @@ -93,6 +94,7 @@ var ( gpioBase int64 clkBase int64 pwmBase int64 + spiBase int64 ) func init() { @@ -100,6 +102,7 @@ func init() { gpioBase = base + gpioOffset clkBase = base + clkOffset pwmBase = base + pwmOffset + spiBase = base + spiOffset } // Pin mode, a pin can be set in Input or Output, Clock or Pwm mode @@ -108,6 +111,7 @@ const ( Output Clock Pwm + Spi ) // State of pin, High / Low @@ -137,9 +141,11 @@ var ( gpioMem []uint32 clkMem []uint32 pwmMem []uint32 + spiMem []uint32 gpioMem8 []uint8 clkMem8 []uint8 pwmMem8 []uint8 + spiMem8 []uint8 ) // Set pin as Input @@ -243,14 +249,17 @@ func PinMode(pin Pin, mode Mode) { shift := (uint8(pin) % 10) * 3 f := uint32(0) + const in = 0 // 000 + const out = 1 // 001 const alt0 = 4 // 100 + const alt4 = 3 // 011 const alt5 = 2 // 010 switch mode { case Input: - f = 0 // 000 + f = in case Output: - f = 1 // 001 + f = out case Clock: switch pin { case 4, 5, 6, 32, 34, 42, 43, 44: @@ -269,6 +278,19 @@ func PinMode(pin Pin, mode Mode) { default: return } + case Spi: + switch pin { + case 7, 8, 9, 10, 11: // SPI0 + f = alt0 + case 35, 36, 37, 38, 39: // SPI0 + f = alt0 + case 16, 17, 18, 19, 20, 21: // SPI1 + f = alt4 + case 40, 41, 42, 43, 44, 45: // SPI2 + f = alt4 + default: + return + } } memlock.Lock() @@ -284,19 +306,19 @@ func PinMode(pin Pin, mode Mode) { func WritePin(pin Pin, state State) { p := uint8(pin) - // Clear register, 10 / 11 depending on bank // Set register, 7 / 8 depending on bank - clearReg := p/32 + 10 + // Clear register, 10 / 11 depending on bank setReg := p/32 + 7 + clearReg := p/32 + 10 memlock.Lock() - defer memlock.Unlock() if state == Low { gpioMem[clearReg] = 1 << (p & 31) } else { gpioMem[setReg] = 1 << (p & 31) } + memlock.Unlock() // not deferring saves ~600ns } // Read the state of a pin @@ -312,14 +334,23 @@ func ReadPin(pin Pin) State { } // Toggle a pin state (high -> low -> high) -// TODO: probably possible to do this much faster without read func TogglePin(pin Pin) { - switch ReadPin(pin) { - case Low: - pin.High() - case High: - pin.Low() + p := uint8(pin) + + setReg := p/32 + 7 + clearReg := p/32 + 10 + levelReg := p/32 + 13 + + bit := uint32(1 << (p & 31)) + + memlock.Lock() + + if (gpioMem[levelReg] & bit) != 0 { + gpioMem[clearReg] = bit + } else { + gpioMem[setReg] = bit } + memlock.Unlock() } // Enable edge event detection on pin. @@ -346,14 +377,14 @@ func DetectEdge(pin Pin, edge Edge) { bit := uint32(1 << (p & 31)) if edge&RiseEdge > 0 { // set bit - gpioMem[renReg] = gpioMem[renReg] | bit + gpioMem[renReg] |= bit } else { // clear bit - gpioMem[renReg] = gpioMem[renReg] &^ bit + gpioMem[renReg] &^= bit } if edge&FallEdge > 0 { // set bit - gpioMem[fenReg] = gpioMem[fenReg] | bit + gpioMem[fenReg] |= bit } else { // clear bit - gpioMem[fenReg] = gpioMem[fenReg] &^ bit + gpioMem[fenReg] &^= bit } gpioMem[edsReg] = bit // to clear outdated detection @@ -387,9 +418,9 @@ func PullMode(pin Pin, pull Pull) { switch pull { case PullDown, PullUp: - gpioMem[pullReg] = gpioMem[pullReg]&^3 | uint32(pull) + gpioMem[pullReg] |= uint32(pull) case PullOff: - gpioMem[pullReg] = gpioMem[pullReg] &^ 3 + gpioMem[pullReg] &^= 3 } // Wait for value to clock in, this is ugly, sorry :( @@ -400,7 +431,7 @@ func PullMode(pin Pin, pull Pull) { // Wait for value to clock in time.Sleep(time.Microsecond) - gpioMem[pullReg] = gpioMem[pullReg] &^ 3 + gpioMem[pullReg] &^= 3 gpioMem[pullClkReg] = 0 } @@ -537,14 +568,14 @@ func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) { func StopPwm() { const pwmCtlReg = 0 const pwen = 1 - pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg] &^ (pwen<<8 | pwen) + pwmMem[pwmCtlReg] &^= pwen<<8 | pwen } // Start pwm for both channels func StartPwm() { const pwmCtlReg = 0 const pwen = 1 - pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg] | pwen<<8 | pwen + pwmMem[pwmCtlReg] |= pwen<<8 | pwen } // Open and memory map GPIO memory range from /dev/mem . @@ -584,6 +615,12 @@ func Open() (err error) { return } + // Memory map spi registers to slice + spiMem, spiMem8, err = memMap(file.Fd(), spiBase) + if err != nil { + return + } + return nil } @@ -619,6 +656,9 @@ func Close() error { if err := syscall.Munmap(pwmMem8); err != nil { return err } + if err := syscall.Munmap(spiMem8); err != nil { + return err + } return nil } diff --git a/spi.go b/spi.go new file mode 100644 index 0000000..41015cc --- /dev/null +++ b/spi.go @@ -0,0 +1,134 @@ +package rpio + +import ( + "errors" +) + +var ( + SpiMapError = errors.New("SPI registers not mapped correctly - are you root?") +) + +const ( + SPI0 = iota // only spi0 supported for now + SPI1 // aux + SPI2 // aux +) + +const ( + csReg = 0 + fifoReg = 1 // TX/RX FIFO + clkDivReg = 2 +) + +// Sets SPI pins of given device to SIP mode +// (CE0, CE1, [CE2], SCLK, MOSI, MISO) +// also reset SPI control register +func SpiBegin(dev int) error { + spiMem[csReg] = 0 // reset spi settings to default + if spiMem[csReg] == 0 { + // this should not read only zeroes after reset -> mem map failed + return SpiMapError + } + + for _, pin := range getSpiPins(dev) { + pin.Mode(Spi) + } + + clearSpiTxRxFifo() + setSpiDiv(128) + return nil +} + +// Sets SPI pins of given device to default (Input) mode +func SpiEnd(dev int) { + var pins = getSpiPins(dev) + for _, pin := range pins { + pin.Mode(Input) + } +} + +// Set (maximal) speed [Hz] of SPI clock +// Param speed may be as big as 125MHz in theory, but +// only values up to 31.25MHz are considered relayable. +func SpiSpeed(speed int) { + const baseFreq = 250 * 1000000 + cdiv := uint32(baseFreq / speed) + setSpiDiv(cdiv) +} + +// Select chip, one of 0, 1, 2 +// for selecting slave on CE0, CE1, or CE2 +func SpiChipSelect(chip int) { // control & status + const csMask = 3 // chip select has 2 bits + + cs := uint32(chip & csMask) + + spiMem[csReg] = spiMem[csReg]&^csMask | cs +} + +// Transmit all bytes in data to slave +// and simultaneously receives bytes from slave to data +func SpiTransfer(data []byte) { // control & status + const ta = 1 << 7 // transfer active + const txd = 1 << 18 // tx fifo can accept data + const rxd = 1 << 17 // rx fifo contains data + const done = 1 << 16 + + length := len(data) + i := 0 // data index + + clearSpiTxRxFifo() + + // set TA = 1 + spiMem[csReg] |= ta + + for i < length { + // Poll TXD writing bytes to SPI_FIFO + for spiMem[csReg]&txd == 0 { + } + spiMem[fifoReg] = uint32(data[i]) + // Poll RXD reading bytes from SPI_FIFO + for spiMem[csReg]&rxd == 0 { + } + data[i] = byte(spiMem[fifoReg]) + i++ + } + + // wait for DONE + for spiMem[csReg]&done == 0 { + } + + // Set TA = 0 + spiMem[csReg] &^= ta +} + +func setSpiDiv(div uint32) { + const divMask = 1<<16 - 1 - 1 // cdiv have 16 bits and must be odd (for some reason) + spiMem[clkDivReg] = div & divMask +} + +func clearSpiTxRxFifo() { + const clearTxRx = 1<<5 | 1<<4 + + spiMem[csReg] |= clearTxRx +} + +func getSpiPins(dev int) []Pin { + switch dev { + case SPI0: + return []Pin{ + 7, 8, 9, 10, 11, + // 35, 36, 37, 38, 39, // only one set of SPI0 can be set in Spi mode at a time + } + case SPI1: + return []Pin{ + 16, 17, 18, 19, 20, 21, + } + case SPI2: + return []Pin{ + 40, 41, 42, 43, 44, 45, + } + default: + return []Pin{} + } +}