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Have you ever ever needed to construct your individual telephone from scratch? Ideally on probably the most ubiquitous electronics prototyping platform for optimum flexibility and minimal ergonomics? Now you may!
In our current product showcase video masking the brand new SparkFun LTE Stick – LARA-R6, I confirmed off a challenge of mine that makes use of the LTE Stick in a enjoyable method; I name it the Breadboard Telephone!
For anybody who hasn’t seen the video, soar to eight minutes into the video to see it in motion!
On this put up, I am going to stroll you thru how one can construct a Breadboard Telephone of your individual! Although a fast head up earlier than we dive in – that is in no way an entire challenge! This was actually simply meant to be a enjoyable demo of the LTE Stick, so not all the things has been thought by means of fully, and the software program has some tough edges and lacking options. So you will have to do some work in the event you actually need this to perform effectively.
Required Supplies
At first, you will want an LTE Stick! That was the unique motivation for this challenge, proper? Do not forget to get a pair LTE antennas too! And you may want a SIM card to connect with a community with a plan that features the options you need; discovering an appropriate SIM card is arguably probably the most troublesome step. As an example, the Hologram SIM card we promote is de facto solely meant for knowledge; sending texts might be hit and miss, and it would not help telephone calls. We bough a Cricket SIM card that labored superb in my telephone, however they suspended service after inserting it into the LTE Stick to a textual content message saying it is an “unsupported machine” even if it labored superb for the two minutes earlier than they stopped the service… I ended up utilizing my private SIM card (service is Ting) and that labored completely superb.
Second, you will want a microcontroller to deal with all the primary logic of interfacing with the consumer inputs/outputs and telling the LTE Stick what to do. You do not actually need something particular or fancy for this, I simply selected the ESP32 Factor Plus as a result of I had one mendacity round on my desk. Nevertheless as a result of its pretty highly effective and has built-in WiFi and Bluetooth, that leaves numerous room for enlargement with this challenge!
Subsequent, you will want a technique to enter and output audio. The LTE Stick has I2S audio pins damaged out to PTH headers particularly for this objective, and is meant to connect with an audio codec. For this, I used the WM8960 audio codec that Pete made a couple of yr in the past, and it really works nice for this software! As well as, you will want a microphone and a speaker to truly measure and create sound waves. I used the SPH8878LR5H-1 MEMS Microphone for its small type issue that may sit proper subsequent to the Factor Plus on the finish of the breadboard, and this PCB mount speaker which simply barely squeezes into the house remaining on the breadboard.
You may want a pair parts for consumer enter and output. After all, I used the Qwiic Keypad for consumer enter – how may you not use that for a telephone challenge! And for displaying stuff to the consumer, I used our Qwiic Micro OLED. In hindsight, this was in all probability not the most effective determination, the display screen is de facto too small for this challenge. I simply grabbed it early on whereas prototyping, and the challenge grew with it, so it grew to become an excessive amount of effort for me to trouble refactoring what was wanted to make use of an even bigger show. If you happen to’re utilizing Qwiic parts, do not forget some Qwiic cables!
Oh, and if you wish to battery energy this challenge, you will want a LiPo battery as effectively! I wasn’t too frightened about working period, so I arbitrarily picked this 400mAh battery, however you may at all times go larger if you’d like it to run for longer!
Lastly, you will want parts to place all the things collectively. You might clearly do that nonetheless you want, however as somebody who’s a bit too captivated with breadboards, I after all needed to stick all the things right into a breadboard. If you happen to select to go down that route, you will additionally want wires to attach all the things. You might use regular breadboard jumper wires, however 22AWG strong core hookup wire is de facto really useful right here; you will additionally want instruments to minimize and strip the wires. And a few soldering can be required to connect headers to the boards, so you will want an iron and solder.
And here is all these components in a single want checklist in case you need to add all of them to cart with a single click on!
Meeting Information
Proper, let’s dive into the meeting! Like talked about above, you should use regular breadboard jumpers if you want, and that is what I did to start with! Nevertheless this challenge requires a number of wires, so it will get messy fairly rapidly, and full dimension jumper forestall you from having the ability to maintain the telephone subsequent to your head correctly. That is the mess I used to be coping with!
So I undoubtedly advocate making customized jumper wires which are the precise size wanted for every section. That is one thing I picked up from Ben Eater, who makes improbable laptop engineering movies on YouTube! This video of his provides a wonderful clarification of the approach. The TLDW is to make use of 22AWG strong core wire, and bend it into the form you want with an additional 0.3″ at every finish to strip the insulation from to insert into the breadboard rails.
Beneath is a closeup of the breadboard I used with all of the parts eliminated so you may see precisely the place every wire goes. Beneath that, we have additionally overlayed the parts so you may see precisely what pin every wire is supposed to connecto to. Be aware that some wires go underneath parts with a view to make it look a bit neater.
One thing else to notice – you will want to decide on how one can energy some parts. I used the three.3V pin coming from the Factor Plus board to energy the microphone and digital IO pin of the audio codec, however the speaker and LTE Stick require a bit extra voltage/energy than the three.3V pin can provide. As a result of I would like this challenge to be moveable, I used the VBAT pin on the Factor Plus, which connects on to the LiPo battery. The restriction right here is that it’s essential to have a battery plugged in for the LTE stick to truly activate correctly. An alternate resolution is to make use of the VUSB pin, which connects on to the USB connector on the Factor Plus; the draw back right here is that it will not be moveable.
As soon as the breadboard is all wired up, the final step of the meeting is to insert your SIM card, join the keypad and show with a pair Qwiic cables, and join the battery. Sadly there’s actually no extra room on the breadboard for these to go, so I simply taped them onto the again of the breadboard.
It is not probably the most elegant resolution, I do know; I simply ran out of time to do one thing higher. One enjoyable suggestion I heard was so as to add these components onto a second breadboard, then join each breadboards with a hinge to create a Breadboard Flip Telephone! I like the thought, nevertheless it’s sadly past what I’ve time for now.
And that is all for the {hardware} meeting! If you happen to determine to recreate this challenge, I might love to listen to in the event you improved on this!
Software program
The final main step is to flash the code onto the microcontroller. All of the code I wrote is written in Arduino and saved within the GitHub repo for the LTE Stick, so you may simply obtain it and flash it onto your board. It does rely upon our new u-blox Mobile Arduino Library, so you will want so as to add that earlier than you may compile and add the code.
Some options are additionally particular to the ESP32 Factor Plus, so in the event you’re utilizing a special growth board, you might have to make some modifications there. And as I discussed initially of this put up, this challenge was initially solely meant to be a demo of a enjoyable method to make use of the LTE Stick reasonably than a last challenge, so the code is in no way excellent. I have never applied a complete lot of options, it is in no way optimized, and it would not deal with all the sting circumstances. It is actually only a proof-of-concept to reveal the challenge and it isn’t prepared for prime time, so you will in all probability need to add some code of your individual to get it working higher.
Utilization
And that is it! Energy it up, ensure to press the ON button on the LTE Stick, and the code will test that all the things is related. Throughout this time, it would use the OLED show and the RGB LED on the Factor Plus to provide standing data, in addition to printing debug messages over Serial in case you want that. Here is what it reveals throughout startup:
The RGB LED can be blue throughout begin up, and alter to inexperienced if profitable, or crimson if there’s a problem detected. If the OLED is working, a message can be displayed on it indicating the precise drawback. For instance, in the event you overlook to press the ON button on the LTE Stick or overlook the SIM card, it would show considered one of these messages on the OLED:
If you happen to’re working into hassle, double test the wiring and take a look at working among the examples from the SparkFun u-blox Mobile Arduino Library. Assuming all goes effectively, the primary menu can be displayed on the OLED.
From there, you may used the keypad to navigate round and do stuff! Basically, the numbers are for consumer enter and deciding on sub-menus indicated on the show, the * button will delete enter or return by means of menus, and the # button is used to complete getting into inputs.
Earlier than diving in although, I might advocate doing a pair issues to confirm all the things is working. First, the code is setup to generate a brief tone by means of the speaker at any time when a secret is pressed on the keypad. Press any of the keypad buttons, and the speaker ought to play a DTMF tone akin to no matter key was pressed. If you happen to do not hear it, you need to troubleshoot that earlier than transferring ahead. Verify the wires are all going to the correct spots, and take a look at working the Arduino examples for the audio codec.
Assuming that works, enter the audio menu and run the loopback take a look at to substantiate whether or not the microphone is working too. Be warned, this takes the microphone output and sends it straight to the speaker, so it would create a number of suggestions and may get very loud in a short time! Urgent the * button ought to cease it, however you may additionally cowl the speaker along with your hand or be able to unplug one thing if wanted. Once more, if this doesn’t work, you need to troubleshoot it earlier than transferring ahead.
If the loopback take a look at works, then meaning just about the entire {hardware} is working appropriately! The final take a look at is to see if you can also make telephone calls. From the primary menu, enter the dial menu, then enter the quantity you need to name. As soon as completed, press the # button to dial the quantity. Assuming all goes effectively, the opposite telephone ought to ring and you need to have the ability to have a dialog with the opposite particular person! And you’ll press the * button to finish the decision.
If in case you have any hassle making the decision, you should definitely strive the audio exams described above, and take a look at among the networking examples from the SparkFun u-blox Mobile Arduino Library. Additionally make it possible for your SIM card works with the LARA-R6, and that your knowledge plan help telephone calls.
Along with telephone calls, you may ship textual content messages! Enter the textual content menu, then enter the message you need to ship. For these conversant in previous flip telephones, I’ve applied a primitive model of T-9 typing! For these unfamiliar, you press the identical button a number of instances to cycle by means of 3 or 4 totally different characters (1 is used for punctuation, 2 is used for ABC, 3 is used for DEF, and so on.). Press the * button to delete a personality, or the # button to complete.
As soon as accomplished, you may then enter the quantity to ship the textual content to, then press the # button once more to ship the textual content. If you happen to get uninterested in getting into individuals’s telephone numbers on a regular basis, you may add them to your velocity dial contact checklist! I’ve applied this as a part of the Arduino code, so you will have to edit that for this function. Open the Breadboard_Phone_Definitions.h file, and close to the highest is the place you may set your contact names and numbers. As soon as accomplished, re-upload the code and any time you are within the dial menu, press the # key to enter the velocity dial menu; every key will correspond to your contact checklist.
The final main function is which you could additionally obtain telephone calls, however that is concerning the extent of what I applied. Like I stated, there’s undoubtedly quite a few options absent, reminiscent of receiving textual content messages. If you happen to select to do that challenge your self, I might love to listen to the way it goes for you and whether or not you increase on my present implementation!
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