From 99a22379fe64903029f2a8a39a16ea4df146ffb7 Mon Sep 17 00:00:00 2001
From: Birte Kristina Friesel <derf@finalrewind.org>
Date: Wed, 17 Jan 2024 20:10:47 +0100
Subject: Initial commit

---
 ccs811.lua | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 ccs811.lua

(limited to 'ccs811.lua')

diff --git a/ccs811.lua b/ccs811.lua
new file mode 100644
index 0000000..8753303
--- /dev/null
+++ b/ccs811.lua
@@ -0,0 +1,66 @@
+local ccs811 = {}
+local device_address = 0x5a
+
+ccs811.mode = nil
+
+function ccs811.start()
+	local ret = true
+	i2c.start(0)
+	if not i2c.address(0, device_address, i2c.TRANSMITTER) then
+		ret = false
+	end
+	i2c.write(0, 0xf4)
+	i2c.stop(0)
+	return ret
+end
+
+function ccs811.setMode(mode)
+	local ret = true
+	i2c.start(0)
+	if not i2c.address(0, device_address, i2c.TRANSMITTER) then
+		ret = false
+	end
+	i2c.write(0, 0x01, bit.lshift(mode, 4))
+	i2c.stop(0)
+	ccs811.mode = mode
+	return ret
+end
+
+function ccs811.setEnv(humi, temp)
+	local ret = true
+	i2c.start(0)
+	if not i2c.address(0, device_address, i2c.TRANSMITTER) then
+		ret = false
+	end
+	i2c.write(0, 0x05, math.floor(humi) * 2, 0, (math.floor(temp) + 25) * 2, 0)
+	i2c.stop(0)
+	return ret
+end
+
+function ccs811.read()
+	local ret = true
+	if ccs811.mode == nil then
+		ccs811.setMode(1)
+		return
+	end
+	i2c.start(0)
+	if not i2c.address(0, device_address, i2c.TRANSMITTER) then
+		ret = false
+	end
+	i2c.write(0, 0x02)
+	i2c.start(0)
+	if not i2c.address(0, device_address, i2c.RECEIVER) then
+		ret = false
+	end
+	local data = i2c.read(0, 6)
+	i2c.stop(0)
+
+	ccs811.eco2 = bit.lshift(string.byte(data, 1), 8) + string.byte(data, 2)
+	ccs811.tvoc = bit.lshift(string.byte(data, 3), 8) + string.byte(data, 4)
+	ccs811.status = string.byte(data, 5)
+	ccs811.err_id = string.byte(data, 6)
+
+	return ret
+end
+
+return ccs811
-- 
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