Testing the Wifi LED controller

Today I started building the Wifi LED controller I wrote about 2 days ago. Not all parts have arrived yet, but all the essential ones are already here, so I could start testing. Let’s see if the I can change the brightness of 3 small pieces of warm white LED strips on a piece of cardboard over Wifi.

I mounted the Wifi module and the stripped MS-35 to a breadboard, connected the two with some wires, added a 3.3V voltage regulator for the Wifi module and waited for the Wifi module to come online.

Wifi UART settingsI already tested the Wifi module ‘standalone’ about a week ago and changed all the settings so that the module would operate like I wanted it to with the built-in Webinterface of the Wifi module; the UART on the Wifi module can work in Transparent or Agreement Transmission mode, the module can act as an Access Point (AP mode) or work in so-called STA mode (like a wireless network card), etcetera. I had already configured all those things, so after power-up the Wifi module was online in a matter of seconds:

Reply from 192.168.10.11: Destination host unreachable.
Reply from 192.168.10.11: Destination host unreachable.
Reply from 192.168.10.11: Destination host unreachable.
Reply from 192.168.10.151: bytes=32 time=2744ms TTL=255
Reply from 192.168.10.151: bytes=32 time=1ms TTL=255
Reply from 192.168.10.151: bytes=32 time=1ms TTL=255
Reply from 192.168.10.151: bytes=32 time=4ms TTL=255
Reply from 192.168.10.151: bytes=32 time=1ms TTL=255

Cool, that’s working again; now let’s see if the UART of the Wifi module is able to communicate with the MS-35. So I added 2 additional wires: one from Wifi-UART_TXD to MS35-RX and another one from Wifi-UART_RXD to MS35-TX. I added a 2nd MS35 LED controller to the database of my Domotica system, started a dev-instance of my system and sent 3 random values for R(ed), G(reen) and B(lue) to the newly added MS-35.

Everything worked as expected – the default program that starts when the MS-35 is powered ended and the brightness of all 3 LED strips changed according to the values I sent. Yep, it’s working 😉

It’s my intention to use a single 12V DC adapter for this LED controller, so just like before I wanted to use a linear voltage regulator to power the Wifi module (3.3V). That means that the 3.3V regulator would have to dissipate (12-3.3) * 0.300 = 2.61W; that’s a lot I guess and I was right – the LD33V regulator I used for testing became too hot to touch, even briefly.

For the sake of ‘learning on the job’ I put a L7805CV I had laying around between the 12V and the LD33V; now the power dissipation was spread over 2 regulators – both still became warm, but not as hot as in the previous single-regulator setup. Another approach I tried was using the 7805 (with heatsink) on the MS-35 PCB but that also led to hot regulators – maybe within specs, but I just don’t like those high temperatures.

So I searched for an alternative, remembered Kyle Gordons comment and decided to give this regulator a try – no need for heatsinks it says! So now I’ll have to wait 2-3 days for this regulator to arrive – which gives me some time to spend time on my solar panel project….never a dull moment!

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