Low Level PIC interfacing (Serial Txt, Twitter, SMS)


Hi Folks…

I am still waiting to get back home to give things a serious try out as
I am on the road still… Another meet up today this time around a
kitchen table with students and several IT teachers and ‘rolled’ my
usual presentation using the WebIOPi digital + Serial interface using
an open wifi LAN out of a recycled router. A demonstration can be set up in minutes. The ability to break out some breadboards with basic digital IO so easily Really does Impress teachers who would normally never touch wires and keep safely to programming. They could all see the level of enrichment and the extra dimension that adding real hardware, models into the real time. It is fun and meaningful for students to work withh. This stuff is now Hot even if most of them had not heard of IoT concepts.

An extra angle close to this simple interface level that I will keep
exploiting is human read-able simple text: Serial or SMS or Twitter.
I think that the ability so send and read meaningful short messages
containing key-words, phrases off a keyboard or phone is a great
feature. Using PIC (picaxe) type systems I find that quite powerful
semi human readable commands can be passed to and from simple u-powered devices. In the case of picaxe it is very easy to Tx and Rx variable data within a single line of PIC.bas type code. It is possible in a
single line command to use a serin delimiter (= keyword) to synch and
crunch variable incoming ascill digital numbers directly into single
bytes and word variables from a free form sentence. A demo I have that handshakes nicely with the serial tab of WebIOPi is a 7 option old school dos type menu that is sent out that a user can remotely respond to. A a range of routines and features deeply embedded at the remote PIC level of a system can thus handshake with human text strings and numbers. There is a level of secuurity here in the simplicity provided a limited range of options are made available.

So my idea is simple: Keep simple serial data available and if SMS /
Twitter type handling can be added and patched to ttyyAMA0 etc on the GPIO. I for one would be keen to use this feature and spread the word and certainly exploit this level of functionality. I have played with twython etc but a more direct type of SMS / Twitter portal somehow into an account Pi I think would be a great feature.

Along this line LoRaWAN ideas ( secure 10km link from a PIC and 3x AA batteries) are now going main stream. LoRa adds 19.5 dB to a radio link budget. The RF Rx works 19.5 dB below the noise floor or against any interfering signals. A typical UART interfaced LoRa radio can connect with 4 jumpers directly TTL Tx, Rx, +3.3 and 0V Again very simple low cost IoT serial over low speed long range radio directly off the Pi GPIO.

Sorry of there are too many ideas in this. I can split them out and provide data, specs and practical information for those wanting to have a play.

~ Andrew


Hi Andrew,

All great suggestions, keep em coming! Definitely we will want to do SMS in near future. No need to take time to split these ideas out.

Once we have our core set of features out we can look into this.



Thanks Andrew !
Serial devices could be easily added, as the commands are mostly text based.
More generally speaking, interfacing with specific devices that embed a specific firmware could be more tricky as we want to try and double check everything. But we can later work together on that.


Just the minimalist raw serial ACII txt window with a CR/LF terminator send button would be a great asset with simple PIC work I do here.

  • The Exisitng WebIOPi serial terminal window will be great
  • The ability to recognize CSV data with a simple graphing gadget
  • File > Save As file.csv or file.txt we use a lot with picaxe system
  • Edit > Copy plot / Copy Data to clipboard
    Reason for putting these ideas forward is that it provides a simple low level tinker and de-bugging space. Last week we used basic WebIOPi on a teacher training / computer science event and they all enjoyed seeing devices connected to software. The Serial port provides a custom portal into the PIC via a simple txt terminal. I do not need to have anything more than a few low level 2400 - 9600 baud rate interface and there is no need to ‘auto detect’ what it is connecting to. ‘Auto Baud’ would be the most advanced feature needed but that is not essential.
    ~ Andrew


We can add the serial terminal and export/import text feature in a later feature. Does not look high priority IMO except if a lot of people ask it.

Auto Baud looks difficult…