diff --git a/content/Hacking my Air Purifier onto Wifi.md b/content/Hacking my Air Purifier onto Wifi.md index 20a5bbe..727a0d9 100644 --- a/content/Hacking my Air Purifier onto Wifi.md +++ b/content/Hacking my Air Purifier onto Wifi.md @@ -61,17 +61,15 @@ Luckily I only blew a fuse on the board and just had to solder a new one on, par This showed me the hack was indeed possible, so I ordered a differential probe off Amazon in order to scope the signals precisely: -``` -- black (GND_S) floats 48 VAC above mains ground -- green (CON3-3) is PWM 0-5 V, higher duty cycle for more speed -- blue (CON3-2) is speed tach. 50% duty cycle, period widens as it gets slower +- Pin 1 (+5V_1A, white) is pretty clean 5.3 V always +- Pin 2 (SIG1) doesn't seem like anything +- Pin 3 (CON3-2) is speed tach. 50% duty cycle, period widens as it gets slower - low speed 80 Hz - medium speed 119 Hz - high speed 200 Hz -- brown (SIG1) doesn't look like anything -- white (15VON/OFF) is 1.5 V when machine is off, noisy 5.3 V when running -- red (+5V_1A) is pretty clean 5.3 V always -``` +- Pin 4 (CON3-3) is PWM 0-5 V, higher duty cycle for more speed +- Pin 5 (GND_S) ground, floats 48 VAC above mains ground +- Pin 6 (15VON/OFF) is 1.5 V when machine is off, noisy 5.3 V when running I wrote a quick Arduino sketch to see if the 0-3.3 V PWM it outputs was enough to control the speed and it was. This, combined with the fact there's 5 V supplied by the ribbon cable meant that the Arduino could be connected simply with three wires, without the need for level shifters or a power supply.