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//go:build mimxrt1062
package runtime
import (
"device/arm"
"device/nxp"
"machine"
"math/bits"
"unsafe"
)
//go:extern _svectors
var _svectors [0]byte
//go:extern _flexram_cfg
var _flexram_cfg [0]byte
//export Reset_Handler
func main() {
// disable interrupts
irq := arm.DisableInterrupts()
// initialize FPU and VTOR, reset watchdogs
initSystem()
// configure core and peripheral clocks/PLLs/PFDs
initClocks()
// copy data/bss sections from flash to RAM
preinit()
// initialize cache and MPU
initCache()
// enable SysTick, GPIO, and peripherals
initPeripherals()
// reenable interrupts
arm.EnableInterrupts(irq)
run()
exit(0)
}
func getRamSizeConfig(itcmKB, dtcmKB uint32) uint32 {
const minKB, disabled = uint32(4), uint32(0)
if itcmKB < minKB {
itcmKB = disabled
}
if dtcmKB < minKB {
dtcmKB = disabled
}
itcmKB = uint32(bits.Len(uint(itcmKB))) << nxp.IOMUXC_GPR_GPR14_CM7_CFGITCMSZ_Pos
dtcmKB = uint32(bits.Len(uint(dtcmKB))) << nxp.IOMUXC_GPR_GPR14_CM7_CFGDTCMSZ_Pos
return (itcmKB & nxp.IOMUXC_GPR_GPR14_CM7_CFGITCMSZ_Msk) |
(dtcmKB & nxp.IOMUXC_GPR_GPR14_CM7_CFGDTCMSZ_Msk)
}
func initSystem() {
// configure SRAM capacity (512K for both ITCM and DTCM)
ramc := uintptr(unsafe.Pointer(&_flexram_cfg))
nxp.IOMUXC_GPR.GPR17.Set(uint32(ramc))
nxp.IOMUXC_GPR.GPR16.Set(0x00200007)
nxp.IOMUXC_GPR.GPR14.Set(getRamSizeConfig(512, 512))
// from Teensyduino
nxp.PMU.MISC0_SET.Set(nxp.PMU_MISC0_REFTOP_SELFBIASOFF)
// install vector table (TODO: initialize interrupt/exception table?)
vtor := uintptr(unsafe.Pointer(&_svectors))
nxp.SystemControl.VTOR.Set(uint32(vtor))
const wdogUpdateKey = 0xD928C520
// disable watchdog powerdown counter
nxp.WDOG1.WMCR.ClearBits(nxp.WDOG_WMCR_PDE_Msk)
nxp.WDOG2.WMCR.ClearBits(nxp.WDOG_WMCR_PDE_Msk)
// disable watchdog
if nxp.WDOG1.WCR.HasBits(nxp.WDOG_WCR_WDE_Msk) {
nxp.WDOG1.WCR.ClearBits(nxp.WDOG_WCR_WDE_Msk)
}
if nxp.WDOG2.WCR.HasBits(nxp.WDOG_WCR_WDE_Msk) {
nxp.WDOG2.WCR.ClearBits(nxp.WDOG_WCR_WDE_Msk)
}
if nxp.RTWDOG.CS.HasBits(nxp.RTWDOG_CS_CMD32EN_Msk) {
nxp.RTWDOG.CNT.Set(wdogUpdateKey)
} else {
nxp.RTWDOG.CNT.Set((wdogUpdateKey >> 0) & 0xFFFF)
nxp.RTWDOG.CNT.Set((wdogUpdateKey >> 16) & 0xFFFF)
}
nxp.RTWDOG.TOVAL.Set(0xFFFF)
nxp.RTWDOG.CS.Set((nxp.RTWDOG.CS.Get() & ^uint32(nxp.RTWDOG_CS_EN_Msk)) | nxp.RTWDOG_CS_UPDATE_Msk)
}
func initPeripherals() {
enableTimerClocks() // activate GPT/PIT clock gates
initSysTick() // enable SysTick
initRTC() // enable real-time clock
enablePinClocks() // activate IOMUXC(_GPR)/GPIO clock gates
initPins() // configure GPIO
enablePeripheralClocks() // activate peripheral clock gates
initUART() // configure UART (initialized first for debugging)
}
func initPins() {
// use fast GPIO for all pins (GPIO6-9)
nxp.IOMUXC_GPR.GPR26.Set(0xFFFFFFFF)
nxp.IOMUXC_GPR.GPR27.Set(0xFFFFFFFF)
nxp.IOMUXC_GPR.GPR28.Set(0xFFFFFFFF)
nxp.IOMUXC_GPR.GPR29.Set(0xFFFFFFFF)
}
func initUART() {
machine.InitSerial()
}
func putchar(c byte) {
machine.Serial.WriteByte(c)
}
func getchar() byte {
for machine.UART1.Buffered() == 0 {
Gosched()
}
v, _ := machine.UART1.ReadByte()
return v
}
func buffered() int {
return machine.UART1.Buffered()
}
func exit(code int) {
abort()
}
func abort() {
for {
arm.Asm("wfe")
}
}
func waitForEvents() {
arm.Asm("wfe")
}
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