So I’ve been continuing to test the Espressif (manufacturer) ESP8266-based WIFI module called the ESP-01 and I’m starting to get somewhere with the “busy s” problem. This board is the more common of a few variations of the board and has power, ground, transmit, receive and 4 control lines called GPIO0, GPIO2, CH_PD and RST. The board runs on 3v3 and consumes up to 250ma (note that some of the smaller Arduino-type boards which have 3v3 power supplies internally, cannot supply this much current. Better to use a 3v3 regulator capable of handling much more. I use one on my home-made Arduinos which can handle up to 1 amp.
Some more hardware info – the pins are not 5v tolerant… clearly the output TX can be connected directly to a 5v Arduino input but you need level conversion for output from Arduino to the WIFI board. I use a resistive divider. 560r from the Arduino output to the WIFI input and 1k2 from there to ground. In normal use including programming you only need 2 of these dividers. This fellow gives a lot more info on hardware.
I’ve done some in-depth tests with an Android mobile phone (Samsung S4) sending commands to the board over a WIFI TCP socket (using NETIO) – and monitored what happens (I use a 1284-based board so I have 2 serial sockets – AWFULLY handy for testing but you could do similar with a bog-standard Arduino). While the phone was sending polling commands constantly, all was working well, until I swapped apps on the phone (or shut it down or had an issue with WIFI signal) in which case it might only get part way through sending the command.
You CANNOT avoid this happening with WIFI by the very nature of it being wireless, there might be a glitch, might be a lack of signal momentarily, interference etc., there will always be occasions when you lose data.
Rather than recover gracefully, the ESP8266 (I imagine) has a flag set to say it is in mid-command… as it pulls in data. A new command coming in is NOT clearing that flag (this is a sheer guess) and so no matter what you do it will just say “busy s” until you reset. One kind gentleman has added a blanket reset command to the ESP8266 but that’s not the answer as you then have to wait for the reset and set up your modes again – what’s needed is for the designers to fix this bug.
SO yesterday afternoon I wrote to them, not very hopeful as I figured they’d be Chinese and might not even understand what I had to say.
Imagine my delight when this came back from ESPRESSIF – a lady by the name of Sue Chen….
Thanks for contacting Espressif Systems!
This is due to a software bug. We will fix this bug in a software release soon.
Have a great day! Thanks.
Sue Chen 陈思祐
This not only confirms that it IS a bug as I thought – but gives us hope that they will soon sort it out – I’ve asked ESPRESSIF to let me know when the update is available and I’ll be sure to put the info in here (make sure you follow my blog – there’s a “follow my tech blog” blue indicator on the upper right of the blog screen).
In the early hours of this morning, I received another email from them asking for debug info – basically which version I’m using – I told them 0019000902 which is the latest though I’m not sure now if it’s the official latest number, as my version has the AT+XRST command which was added by a third party (detained in this or previous blog items)… which WORKS but really you don’t want to be resetting the unit as it takes too long and happens too often.
ESPRESSIF confirmed that the issue is incomplete commands – I suggested that such commands should be quickly timed out… you might even be sending data with AT+CIPSEND=ID,value,data and if it’s a mobile device sending this, it could fail at ANY point… the ESP8266 needs to recover from this rapidly and move on without losing the current mode – this should be simple enough – if I were designing this I’d simply time out commands. So let’s say you are talking to the board at 115k baud, that’s 10k characters a second – let’s say 1k characters a second to be charitable… so if there is a gap of say 1ms or more mid-command, or an unexpected character then the unit should simply wind back and start looking for AT…. I believe this would solve the problem…
I’m getting excited already…I could be using these boards in so many projects… #ESP8266 #ESPRESSIF #ESP-01
Further back on this blog you’ll see other items on the subject of the ESP8266 as I fumbled my way along with very little info. There is also some technical blogging regarding Arduino and similar on my home blog
There is some code for the ESP8266 on this blog for the Teensy 3.1 … http://forum.pjrc.com/threads/26873-ESP8266-with-Teensy