I have to say, it felt a little like Christmas today when the Correos post-lady turned up with a plastic container full of packages from China for me.
Among the many items in today’s post were the two you see above – a WEMOS board (i.e. ESP-12 + power supply) which includes an OLED display. As you’ll know I’ve recently added the SD1306 display to the commands on my ESP8266 code – looks like they’ve done the same but gone a stage further and added the actual display to the board.
(While I'm here - note the site is now https:// rather than http:// - if anyone has issues (despite refreshing the browser) - do please let me know.
To keep costs down they’ve used the raw display and added their own electronics – but it still ends up as an I2c peripheral. I hope later this week to ensure my own software will handle this as the board (AliExpress) is dirt cheap and I can see a bright future for these little displays.
They call the board the Wemos D-Duino and about my only comment up to now is that it arrived with the display a tad loose and not lined up as they’ve used double-sided sellotape to hold it in place. When will people think – that stuff just does not work! So a little Gorilla Glue will be added today.
The second item that turned up was a (supposedly) Wemos uninterruptible supply (we’ve discussed the subject of these supplies and our expectations of them many times). The battery was NOT included but luckily I had an Ultrafire handy – I also have a wide range of ex-laptop batteries which also do the job. I had planned to give this board (I have two of them) a good hammering this week and I’ll let you know how that goes but as it turns out I can tell you very quickly and succinctly - it DOESN'T. The Wemos D-Duino actually powers up in demo mode with the display cycling (and very pretty with it) so with a battery that had been sitting around for months without charge, I didn’t have to wait long for the display to go blank.
With the battery down to 2.89v, nothing was coming out of the power unit. Without disconnecting the load, I plugged the power unit into USB power (little micro-USB connector on the underside.
I refer you to the AliExpress specification:
LED indicate(Green means full,Red means charging)
The underside red light came on, sure enough but the display did not immediately spring to live – so I left the board to charge. No matter what I did, the ESP unit would not spring to life until I disconnected it (at which point charging began) and reconnected it (at which point charging stopped).
I put a meter on the battery and noting that a red light had appeared on the underside of the power board I measured the battery voltage. It did not seem to be rising. Indeed if anything it was going down! I disconnected the load – and reconnected. The Wemos came on for an instant then went off. The voltage at this point was now down to 2.76v. Everything was running cold on the power unit. This was not what I was expecting.
I disconnected the load and reconnected. Now the power started to rise. When it got to 3.2v I reconnected the load and the display lit up. I disconnected the input and let the power drop again. At exactly 2.57v the output went off. Of course the battery voltage then shot up to 2.84v– no output. I plugged the power back in.
The Wemos 1860 Shield (here we see both together) https://goo.gl/isiHaF appears to be totally and completely useless, refusing to charge from standby state while the load is connected. If you turn the load off – it charges. This is not the first time we’ve seen this on arbitrary battery supply boards – but on a dedicated product? Is this Candid Camera?? You may have read elsewhere that I HAVE had very cheap boards from China which would ONLY fail to start up from completely flat - something that is easy to get around with a little additional circuitry - in this case however the power cuts out at an entirely reasonable voltage and won't come back on - so you can't even circumvent that with an additional circuit.
Read the comments as my testing is down there. Conclusion while waiting to hear from the supplier and up to now they are NOT responding - further my review has failed to appear on AliExpress among the most likely artificial positive comments - AVOID THIS ONE LIKE THE PLAGUE.
There does seem to be an issue here - I've not seen ONE of this kind of supply, able to supply 2 amps or more and charge at that rate (otherwise there's little point in supplying that kind of current) that ACTUALLY WORKS and keeps on working.
More on the rest of today’s rather large postbag later.