add：Air780EPM 区分下接单个18B20和不同pin上接多个18b20的情况

module/Air780EPM/demo/onewire/onewire_multi_18b20_swich_read/main.lua

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+PROJECT = "DS18B20_GPIO_SWITCH_READ_temperature"
+VERSION = "1.0.0"
+sys = require("sys")
+log.style(1)
+
+
+require"switch_read"
+
+sys.run()

module/Air780EPM/demo/onewire/onewire_multi_18b20_swich_read/switch_read.lua

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+
+pm.ioVol(pm.IOVOL_ALL_GPIO, 3300) -- 所有GPIO高电平输出3.3V(方便使用VDD_EXT给18B20供电)
+gpio.setup(2, 1) --GPIO2控制780EPM开发板V1.3版本camera电源打开和关闭
+gpio.setup(31, 1) -- GPIO31控制780EPM开发板V1.4版本camera电源打开和关闭
+
+local onewire_pin = 54 --18B20接的pin 54脚
+
+
+pins.setup(onewire_pin, "ONEWIRE") -- PAD54脚既是GPIO3也是cam_mclk 
+
+--读取当前pin脚上的18B20温度
+local function read_ds18b20(id)
+log.info("读取温度",id)
+    local tbuff = zbuff.create(10)
+    local succ, crc8c, range, t
+    local rbuff = zbuff.create(9)
+    tbuff:write(0x55)
+    tbuff:copy(nil, id)
+    tbuff:write(0xb8)
+  
+    tbuff[tbuff:used() - 1] = 0x44
+    succ = onewire.tx(0, tbuff, false, true, true)
+    if not succ then
+        return
+    end
+
+    succ = onewire.reset(0, true)
+    if not succ then
+        return
+    end
+    if onewire.bit(0) > 0 then
+        log.info("温度转换完成")
+    end
+    tbuff[tbuff:used() - 1] = 0xbe
+    succ = onewire.tx(0, tbuff, false, true, true)
+    if not succ then
+        return
+    end
+    succ, rx_data = onewire.rx(0, 9, nil, rbuff, false, false, false)
+    crc8c = crypto.crc8(rbuff:toStr(0, 8), 0x31, 0, true)
+    if crc8c == rbuff[8] then
+        range = (rbuff[4] >> 5) & 0x03
+        -- rbuff[0] = 0xF8
+        -- rbuff[1] = 0xFF
+        t = rbuff:query(0, 2, false, true)
+        t = t * (5000 >> range)
+        t = t / 10000
+        log.info("当前温度", t,"原始值为",mcu.x32(rbuff[8]))
+    else
+        log.info("RAM DATA CRC校验不对", mcu.x32(crc8c), mcu.x32(rbuff[8]))
+        return
+    end
+
+end
+
+--初始化当前pin脚上的18B20，并读取18B20的唯一识别ID
+local function test_ds18b20()
+    local succ, rx_data
+    local id = zbuff.create(8)
+    local crc8c
+    onewire.init(0) -- 初始化单总线
+    onewire.timing(0, false, 0, 500, 500, 15, 240, 70, 1, 15, 10, 2)
+    id:set() -- 清空id
+    succ, rx_data = onewire.rx(0, 8, 0x33, id, false, true, true)
+    if succ then
+        if id[0] == 0x28 then
+            crc8c = crypto.crc8(id:query(0, 7), 0x31, 0, true)
+            if crc8c == id[7] then
+                log.info("探测到DS18B20", "18B20对应唯一ID为", id:query(0, 7):toHex())
+                read_ds18b20(id)
+                -- log.info("DS18B20离线，重新探测")
+            else
+                log.info("ROM ID CRC校验不对", mcu.x32(crc8c), mcu.x32(id[7]))
+            end
+        else
+            log.info("ROM ID不正确", mcu.x32(id[0]))
+        end
+    else
+        log.info("没有检测到DS18B20")
+    end
+end
+
+local switchover_pin = gpio.PWR_KEY --选择powerkey作为切换18B20读数的信号脚
+
+gpio.debounce(switchover_pin, 100) --设置防抖
+
+
+--设置powerkey按下和抬起的功能(18B20温度的取值再54pin和56pin之间切换)
+--如果客户需要其他pin(22/54/56/78)则改动switchover_pin为用户需要的即可
+--注意，由于powerkey不能做单边沿触发，所以一次按下和抬起的动作，会触发两次切换pin
+--看效果的话，可以先一直按住powerkey几秒，再松开
+gpio.setup(switchover_pin, function()
+    log.info("Touch_pin", switchover_pin, "被触发")
+    log.info("当前单总线pad", onewire_pin)
+    if onewire_pin == 54 then
+        log.info("给PAD" .. onewire_pin .. "配置到GPIO3上去", pins.setup(onewire_pin, "GPIO3"))
+        log.info("给GPIO3设置为高电平输出模式",gpio.setup(3,1))--一定要执行gpio.setup，至于是哪种模式，用户根据自身需求
+        onewire_pin = 56
+    else
+        log.info("给PAD" .. onewire_pin .. "配置到GPIO7上去", pins.setup(onewire_pin, "GPIO7"))
+        log.info("给GPIO7设置为高电平输出模式",gpio.setup(7,1))
+
+        onewire_pin = 54
+    end
+    log.info("设置后单总线pad", onewire_pin)
+
+    onewire.deinit(0) -- 切换的时候一定要先关闭单总线，在读取的时候重新初始化
+
+    log.info("给" .. onewire_pin .. "配置到onewire上去", pins.setup(onewire_pin, "ONEWIRE"))
+    sys.publish("powerkey被按下")
+end, gpio.PULLUP, gpio.RISING)
+
+sys.taskInit(function()
+    while 1 do
+        -- sys.waitUntil("powerkey被按下")
+        log.info("1S后读取"..onewire_pin.."脚上的18B20")
+        sys.wait(1000)
+        log.info("开始读取18B20")
+        test_ds18b20()
+    end
+end)
+
+
+
+

module/Air780EPM/demo/onewire/onewire_single_18b20/main.lua

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+PROJECT = "onewiredemo"
+VERSION = "1.0.0"
+sys = require("sys")
+log.style(1)
+
+--[[
+接线说明:
+   DS18B20    Air780EPM
+1. GND    -> GND
+2. VDD    -> 3.3V
+3. DATA    -> GPIO2
+
+注意:
+1. 3.3v在老版本的开发板上没有引脚, 所以需要外接, 一定要确保共地
+2. ONEWIRE功能支持在4个引脚使用, 但硬件通道只有一个, 默认是GPIO2
+3. 如需切换到其他脚, 参考如下切换逻辑, 选其中一种
+
+mcu.altfun(mcu.ONEWIRE, 0, 17, 4, 0) -- GPIO2, 也就是默认值
+mcu.altfun(mcu.ONEWIRE, 0, 18, 4, 0) -- GPIO3
+mcu.altfun(mcu.ONEWIRE, 0, 22, 4, 0) -- GPIO7
+mcu.altfun(mcu.ONEWIRE, 0, 53, 4, 0) -- GPIO28
+]]
+
+local function read_ds18b20(id)
+    local tbuff = zbuff.create(10)
+    local succ,crc8c,range,t
+    local rbuff = zbuff.create(9)
+    --如果有多个DS18B20,需要带上ID
+    tbuff:write(0x55)
+    tbuff:copy(nil, id)
+    tbuff:write(0xb8)
+    --如果只有1个DS18B20,就用无ID方式
+    --tbuff:write(0xcc,0xb8)
+    while true do
+        tbuff[tbuff:used() - 1] = 0x44
+        succ = onewire.tx(0, tbuff, false, true, true)
+        if not succ then
+            return
+        end
+        while true do
+            succ = onewire.reset(0, true)
+            if not succ then
+                return
+            end
+            if onewire.bit(0) > 0 then
+                log.info("温度转换完成")
+                break
+            end
+            sys.wait(10)
+        end
+        tbuff[tbuff:used() - 1] = 0xbe
+        succ = onewire.tx(0, tbuff, false, true, true)
+        if not succ then
+            return
+        end
+        succ,rx_data = onewire.rx(0, 9, nil, rbuff, false, false, false)
+        crc8c = crypto.crc8(rbuff:toStr(0,8), 0x31, 0, true)
+        if crc8c == rbuff[8] then
+            range = (rbuff[4] >> 5) & 0x03
+            -- rbuff[0] = 0xF8
+            -- rbuff[1] = 0xFF
+            t = rbuff:query(0,2,false,true)
+            t = t * (5000 >> range)
+            t = t / 10000
+            log.info(t)
+        else
+            log.info("RAM DATA CRC校验不对",  mcu.x32(crc8c), mcu.x32(rbuff[8]))
+            return
+        end
+        sys.wait(500)
+    end
+end
+
+local function test_ds18b20()
+    local succ,rx_data
+    local id = zbuff.create(8)
+
+    local crc8c
+    onewire.init(0)
+    onewire.timing(0, false, 0, 500, 500, 15, 240, 70, 1, 15, 10, 2)
+    while true do
+        id:set() --清空id
+        succ,rx_data = onewire.rx(0, 8, 0x33, id, false, true, true)
+        if succ then
+            if id[0] == 0x28 then
+                crc8c = crypto.crc8(id:query(0,7), 0x31, 0, true)
+                if crc8c == id[7] then
+                    log.info("探测到DS18B20", id:query(0, 7):toHex())
+                    read_ds18b20(id)
+                    log.info("DS18B20离线，重新探测")
+                else
+                    log.info("ROM ID CRC校验不对",  mcu.x32(crc8c), mcu.x32(id[7]))
+                end
+            else
+                log.info("ROM ID不正确", mcu.x32(id[0]))
+            end
+        end
+        log.info("没有检测到DS18B20, 5秒后重试")
+        sys.wait(5000)
+
+    end
+    
+
+end
+
+if onewire then
+    sys.taskInit(test_ds18b20)
+else
+    log.info("no onewire")
+end
+
+sys.run()