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//go:build nrf52840 || nrf52833
package machine
import (
"device/nrf"
"unsafe"
)
// I2C on the NRF528xx.
type I2C struct {
Bus *nrf.TWIM_Type // Called Bus to align with Bus field in nrf51
BusT *nrf.TWIS_Type
mode I2CMode
}
// There are 2 I2C interfaces on the NRF.
var (
I2C0 = &I2C{Bus: nrf.TWIM0, BusT: nrf.TWIS0}
I2C1 = &I2C{Bus: nrf.TWIM1, BusT: nrf.TWIS1}
)
func (i2c *I2C) enableAsController() {
i2c.Bus.ENABLE.Set(nrf.TWIM_ENABLE_ENABLE_Enabled)
}
func (i2c *I2C) enableAsTarget() {
i2c.BusT.ENABLE.Set(nrf.TWIS_ENABLE_ENABLE_Enabled)
}
func (i2c *I2C) disable() {
i2c.Bus.ENABLE.Set(0)
}
// Tx does a single I2C transaction at the specified address (when in controller mode).
//
// 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.
func (i2c *I2C) Tx(addr uint16, w, r []byte) (err error) {
i2c.Bus.ADDRESS.Set(uint32(addr))
i2c.Bus.EVENTS_STOPPED.Set(0)
i2c.Bus.EVENTS_ERROR.Set(0)
i2c.Bus.EVENTS_RXSTARTED.Set(0)
i2c.Bus.EVENTS_TXSTARTED.Set(0)
i2c.Bus.EVENTS_LASTRX.Set(0)
i2c.Bus.EVENTS_LASTTX.Set(0)
i2c.Bus.EVENTS_SUSPENDED.Set(0)
// Configure for a single shot to perform both write and read (as applicable)
if len(w) != 0 {
i2c.Bus.TXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&w[0]))))
i2c.Bus.TXD.MAXCNT.Set(uint32(len(w)))
// If no read, immediately signal stop after TX
if len(r) == 0 {
i2c.Bus.SHORTS.Set(nrf.TWIM_SHORTS_LASTTX_STOP)
}
}
if len(r) != 0 {
i2c.Bus.RXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&r[0]))))
i2c.Bus.RXD.MAXCNT.Set(uint32(len(r)))
// Auto-start Rx after Tx and Stop after Rx
i2c.Bus.SHORTS.Set(nrf.TWIM_SHORTS_LASTTX_STARTRX | nrf.TWIM_SHORTS_LASTRX_STOP)
}
// Fire the transaction
i2c.Bus.TASKS_RESUME.Set(1)
if len(w) != 0 {
i2c.Bus.TASKS_STARTTX.Set(1)
} else if len(r) != 0 {
i2c.Bus.TASKS_STARTRX.Set(1)
}
// Wait until transaction stopped to ensure buffers fully processed
for i2c.Bus.EVENTS_STOPPED.Get() == 0 {
// Allow scheduler to run
gosched()
// Handle errors by ensuring STOP sent on bus
if i2c.Bus.EVENTS_ERROR.Get() != 0 {
if i2c.Bus.EVENTS_STOPPED.Get() == 0 {
// STOP cannot be sent during SUSPEND
i2c.Bus.TASKS_RESUME.Set(1)
i2c.Bus.TASKS_STOP.Set(1)
}
err = twiCError(i2c.Bus.ERRORSRC.Get())
}
}
return
}
// Listen starts listening for I2C requests sent to specified address
//
// addr is the address to listen to
func (i2c *I2C) Listen(addr uint8) error {
i2c.BusT.ADDRESS[0].Set(uint32(addr))
i2c.BusT.CONFIG.Set(nrf.TWIS_CONFIG_ADDRESS0_Enabled)
i2c.BusT.EVENTS_STOPPED.Set(0)
i2c.BusT.EVENTS_ERROR.Set(0)
i2c.BusT.EVENTS_RXSTARTED.Set(0)
i2c.BusT.EVENTS_TXSTARTED.Set(0)
i2c.BusT.EVENTS_WRITE.Set(0)
i2c.BusT.EVENTS_READ.Set(0)
return nil
}
// WaitForEvent blocks the current go-routine until an I2C event is received (when in Target mode).
//
// The passed buffer will be populated for receive events, with the number of bytes
// received returned in count. For other event types, buf is not modified and a count
// of zero is returned.
//
// For request events, the caller MUST call `Reply` to avoid hanging the i2c bus indefinitely.
func (i2c *I2C) WaitForEvent(buf []byte) (evt I2CTargetEvent, count int, err error) {
i2c.BusT.RXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&buf[0]))))
i2c.BusT.RXD.MAXCNT.Set(uint32(len(buf)))
i2c.BusT.TASKS_PREPARERX.Set(nrf.TWIS_TASKS_PREPARERX_TASKS_PREPARERX_Trigger)
i2c.Bus.TASKS_RESUME.Set(1)
for i2c.BusT.EVENTS_STOPPED.Get() == 0 &&
i2c.BusT.EVENTS_READ.Get() == 0 {
gosched()
if i2c.BusT.EVENTS_ERROR.Get() != 0 {
i2c.BusT.EVENTS_ERROR.Set(0)
return I2CReceive, 0, twisError(i2c.BusT.ERRORSRC.Get())
}
}
count = 0
evt = I2CFinish
err = nil
if i2c.BusT.EVENTS_WRITE.Get() != 0 {
i2c.BusT.EVENTS_WRITE.Set(0)
// Data was sent to this target. We've waited for
// READ or STOPPED event, so transmission should be
// complete.
count = int(i2c.BusT.RXD.AMOUNT.Get())
evt = I2CReceive
} else if i2c.BusT.EVENTS_READ.Get() != 0 {
i2c.BusT.EVENTS_READ.Set(0)
// Data is requested from this target, hw will stretch
// the controller's clock until there is a reply to
// send
evt = I2CRequest
} else if i2c.BusT.EVENTS_STOPPED.Get() != 0 {
i2c.BusT.EVENTS_STOPPED.Set(0)
evt = I2CFinish
}
return
}
// Reply supplies the response data the controller.
func (i2c *I2C) Reply(buf []byte) error {
i2c.BusT.TXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&buf[0]))))
i2c.BusT.TXD.MAXCNT.Set(uint32(len(buf)))
i2c.BusT.EVENTS_STOPPED.Set(0)
// Trigger Tx
i2c.BusT.TASKS_PREPARETX.Set(nrf.TWIS_TASKS_PREPARETX_TASKS_PREPARETX_Trigger)
// Block, waiting for Tx to complete
for i2c.BusT.EVENTS_STOPPED.Get() == 0 {
gosched()
if i2c.BusT.EVENTS_ERROR.Get() != 0 {
return twisError(i2c.BusT.ERRORSRC.Get())
}
}
i2c.BusT.EVENTS_STOPPED.Set(0)
return nil
}
// twiCError converts an I2C controller error to Go
func twiCError(val uint32) error {
if val == 0 {
return nil
} else if val&nrf.TWIM_ERRORSRC_OVERRUN_Msk == nrf.TWIM_ERRORSRC_OVERRUN {
return errI2CBusError
} else if val&nrf.TWIM_ERRORSRC_ANACK_Msk == nrf.TWIM_ERRORSRC_ANACK {
return errI2CAckExpected
} else if val&nrf.TWIM_ERRORSRC_DNACK_Msk == nrf.TWIM_ERRORSRC_DNACK {
return errI2CAckExpected
}
return errI2CBusError
}
// twisError converts an I2C target error to Go
func twisError(val uint32) error {
if val == 0 {
return nil
} else if val&nrf.TWIS_ERRORSRC_OVERFLOW_Msk == nrf.TWIS_ERRORSRC_OVERFLOW {
return errI2COverflow
} else if val&nrf.TWIS_ERRORSRC_DNACK_Msk == nrf.TWIS_ERRORSRC_DNACK {
return errI2CAckExpected
} else if val&nrf.TWIS_ERRORSRC_OVERREAD_Msk == nrf.TWIS_ERRORSRC_OVERREAD {
return errI2COverread
}
return errI2CBusError
}
var (
Watchdog = &watchdogImpl{}
)
const (
// WatchdogMaxTimeout in milliseconds (approx 36h)
WatchdogMaxTimeout = (0xffffffff * 1000) / 32768
)
type watchdogImpl struct {
}
// Configure the watchdog.
//
// This method should not be called after the watchdog is started and on
// some platforms attempting to reconfigure after starting the watchdog
// is explicitly forbidden / will not work.
func (wd *watchdogImpl) Configure(config WatchdogConfig) error {
// 32.768kHz counter
crv := int32((int64(config.TimeoutMillis) * 32768) / 1000)
nrf.WDT.CRV.Set(uint32(crv))
// One source
nrf.WDT.RREN.Set(0x1)
// Run during sleep
nrf.WDT.CONFIG.Set(nrf.WDT_CONFIG_SLEEP_Run)
return nil
}
// Starts the watchdog.
func (wd *watchdogImpl) Start() error {
nrf.WDT.TASKS_START.Set(nrf.WDT_TASKS_START_TASKS_START)
return nil
}
// Update the watchdog, indicating that `source` is healthy.
func (wd *watchdogImpl) Update() {
// 0x6E524635 = magic value from datasheet
nrf.WDT.RR[0].Set(0x6E524635)
}
|
