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https://github.com/tinygo-org/tinygo.git
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Ayke van Laethem
73 lines
2.0 KiB
Go
73 lines
2.0 KiB
Go
//go:build esp32
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package runtime
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import (
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"device"
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"device/esp"
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"machine"
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)
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// This is the function called on startup right after the stack pointer has been
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// set.
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//
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//export main
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func main() {
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// Disable the protection on the watchdog timer (needed when started from
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// the bootloader).
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esp.RTC_CNTL.WDTWPROTECT.Set(0x050D83AA1)
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// Disable both watchdog timers that are enabled by default on startup.
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// Note that these watchdogs can be protected, but the ROM bootloader
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// doesn't seem to protect them.
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esp.RTC_CNTL.WDTCONFIG0.Set(0)
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esp.TIMG0.WDTCONFIG0.Set(0)
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// Switch SoC clock source to PLL (instead of the default which is XTAL).
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// This switches the CPU (and APB) clock from 40MHz to 80MHz.
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// Options:
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// RTC_CNTL_CLK_CONF_SOC_CLK_SEL: PLL (1) (default XTAL)
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// RTC_CNTL_CLK_CONF_CK8M_DIV_SEL: 2 (default)
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// RTC_CNTL_CLK_CONF_DIG_CLK8M_D256_EN: Enable (default)
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// RTC_CNTL_CLK_CONF_CK8M_DIV: divide by 256 (default)
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// The only real change made here is modifying RTC_CNTL_CLK_CONF_SOC_CLK_SEL,
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// but setting a fixed value produces smaller code.
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esp.RTC_CNTL.CLK_CONF.Set((1 << esp.RTC_CNTL_CLK_CONF_SOC_CLK_SEL_Pos) |
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(2 << esp.RTC_CNTL_CLK_CONF_CK8M_DIV_SEL_Pos) |
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(1 << esp.RTC_CNTL_CLK_CONF_DIG_CLK8M_D256_EN_Pos) |
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(1 << esp.RTC_CNTL_CLK_CONF_CK8M_DIV_Pos))
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// Switch CPU from 80MHz to 160MHz. This doesn't affect the APB clock,
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// which is still running at 80MHz.
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esp.DPORT.CPU_PER_CONF.Set(1) // PLL_CLK / 2, see table 3-3 in the reference manual
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// Clear .bss section. .data has already been loaded by the ROM bootloader.
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// Do this after increasing the CPU clock to possibly make startup slightly
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// faster.
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clearbss()
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// Initialize UART.
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machine.InitSerial()
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// Initialize main system timer used for time.Now.
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initTimer()
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// Initialize the heap, call main.main, etc.
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run()
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// Fallback: if main ever returns, hang the CPU.
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exit(0)
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}
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//go:extern _sbss
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var _sbss [0]byte
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//go:extern _ebss
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var _ebss [0]byte
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func abort() {
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for {
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device.Asm("waiti 0")
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}
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}
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