1 files changed, 86 insertions, 0 deletions
diff --git a/sen5x.lua b/sen5x.lua
new file mode 100644
index 0000000..afc9970
--- /dev/null
+++ b/sen5x.lua
@@ -0,0 +1,86 @@
+local sen5x = {}
+local device_address = 0x69
+
+sen5x.bus_id = 0
+
+function sen5x.start()
+	i2c.start(sen5x.bus_id)
+	if not i2c.address(sen5x.bus_id, device_address, i2c.TRANSMITTER) then
+		return false
+	end
+	i2c.write(sen5x.bus_id, {0x00, 0x21})
+	i2c.stop(sen5x.bus_id)
+	return true
+end
+
+function sen5x.stop()
+	i2c.start(sen5x.bus_id)
+	if not i2c.address(sen5x.bus_id, device_address, i2c.TRANSMITTER) then
+		return false
+	end
+	i2c.write(sen5x.bus_id, {0x01, 0x04})
+	i2c.stop(sen5x.bus_id)
+	return true
+end
+
+function sen5x.read_value(data, index)
+	local val = string.byte(data, index) * 256 + string.byte(data, index+1)
+	if val == 0xffff or val == 0x7fff then
+		val = nil
+	end
+	return val
+end
+
+function sen5x.prepare_read()
+	i2c.start(sen5x.bus_id)
+	if not i2c.address(sen5x.bus_id, device_address, i2c.TRANSMITTER) then
+		return false
+	end
+	i2c.write(sen5x.bus_id, {0x03, 0xc4})
+	i2c.stop(sen5x.bus_id)
+	return true
+end
+
+function sen5x.read()
+	i2c.start(sen5x.bus_id)
+	if not i2c.address(sen5x.bus_id, device_address, i2c.RECEIVER) then
+		return false
+	end
+	local data = i2c.read(sen5x.bus_id, 24)
+	i2c.stop(sen5x.bus_id)
+	sen5x.pm1 = sen5x.read_value(data, 1)
+	sen5x.pm2_5 = sen5x.read_value(data, 4)
+	sen5x.pm4 = sen5x.read_value(data, 7)
+	sen5x.pm10 = sen5x.read_value(data, 10)
+	sen5x.humidity = sen5x.read_value(data, 13)
+	sen5x.temperature = sen5x.read_value(data, 16)
+	sen5x.voc = sen5x.read_value(data, 19)
+	sen5x.nox = sen5x.read_value(data, 22)
+	return true
+end
+
+function sen5x.prepare_get_product()
+	i2c.start(sen5x.bus_id)
+	if not i2c.address(sen5x.bus_id, device_address, i2c.TRANSMITTER) then
+		return false
+	end
+	i2c.write(sen5x.bus_id, {0xd0, 0x14})
+	i2c.stop(sen5x.bus_id)
+	return true
+end
+
+function sen5x.get_product()
+	i2c.start(sen5x.bus_id)
+	if not i2c.address(sen5x.bus_id, device_address, i2c.RECEIVER) then
+		return nil
+	end
+	local data = i2c.read(sen5x.bus_id, 48)
+	i2c.stop(sen5x.bus_id)
+	local ret = ""
+	ret = ret .. string.sub(data, 1, 2)
+	ret = ret .. string.sub(data, 4, 5)
+	ret = ret .. string.sub(data, 7, 7)
+	return ret
+end
+
+return sen5x