DACを使用した波形生成

[xcd0]

PWM変調で十分だが、DACを使用してよりきれいな正弦波を出力できるようにしてもよいかなと

[xcd0]

tinygoのSPIのDACのコード

https://blueeyes.sakura.ne.jp/2020/06/05/3240/#:~:text=%E3%81%A3%E3%81%A6%E3%81%BF%E3%81%BE%E3%81%99%E3%80%82-,mcp4922,-MicroChip%20%E7%A4%BE%E3%81%AE

package main

import (
    "machine"
    "time"
)

const nss = machine.Pin(machine.PA4)

func main() {
    machine.SPI0.Configure(machine.SPIConfig{
        Frequency: 100000,
        Mode: 0,
    })

    nss.Configure(machine.PinConfig{Mode: machine.PinOutput})
    nss.High()

    const header = 0b0111
    var value uint16
    for {
        value += 8
        if (value & 0xF000) != 0 {
            value = 0
        }
        send((header << 12) | value)
        time.Sleep(time.Millisecond * 1)
    }
}

func send(data uint16) {
    tx := make([]byte, 2)
    rx := make([]byte, 2)

    tx[0] = byte(data >> 8)
    tx[1] = byte(data & 0xFF)

    nss.Low()
    machine.SPI0.Tx(tx, rx)
    nss.High()
}

その下にI2CでLCDを動かすコードがある

package main

import (
    "machine"
    "time"
)

const led = machine.LED
func main() {
    led.Configure(machine.PinConfig{Mode: machine.PinOutput})

    machine.I2C0.Configure(machine.I2CConfig{})
    err := lcdInit()
    if err != nil {
    }
    time.Sleep(time.Millisecond * 200)

    for {
        lcdString("Hello")
        time.Sleep(time.Millisecond * 500)
    }
}

func lcdInit() error {
    cmds := []byte{0x38, 0x39, 0x14, 0x73, 0x56, 0x6C, 0x38, 0x01, 0x0C}

    for i := 0; i < len(cmds); i++ {
        err := machine.I2C0.Tx(0x7c >> 1, []byte{0x00, cmds[i]}, nil)
        if err != nil {
            return err
        }
        time.Sleep(time.Millisecond * 100)
    }
    return nil
}

func lcdString(str string) {
    for i := 0; i < len(str); i++ {
        machine.I2C0.Tx(0x7c >> 1, []byte{0x40, str[i]}, nil)
        time.Sleep(time.Millisecond * 1)
    }
}