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    27Mhz - Radio Ideas

    C-3PO
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  C-3PO Tue May 10, 2022 4:35 pm

    Hi David,

    I am going to do the lottery tonight :) - 5 mins in and I have read AX5043 register values - so the journey starts....

    Is it possible that you tested the boards you sent me with some other software?

    See image and code below

    Code:

    // ***********************************************************************************************
    //  Name:       SPI_readRegs_003
    //  Date:       10 May 2022
    //  Brief:      Crude SPI test - read write
    //  Author:     Jonathan Askey
    // ***********************************************************************************************

    /*  SPI connections
     *  Uno/Nano      AX5043
     *  MOSI  11      17
     *  MISO  12      16
     *  SCK   13      15
     *  SS    10      14
     *  3.3v          23
     *  GND            6
     */


    #include <SPI.h>

    uint8_t slaveSelectPin=10; // CS Chip Select

    uint8_t regAddr;
    uint8_t regVal;


    void setup() {
     
      digitalWrite(slaveSelectPin, HIGH);
      pinMode(slaveSelectPin, OUTPUT); // set the SS pin as an output
      SPI.begin();         // initialize the SPI library
      SPI.beginTransaction(SPISettings(14000000, MSBFIRST, SPI_MODE0));
      
      Serial.begin(9600);
    }

    void loop() {

      digitalWrite(10, LOW);            // set the SS pin to LOW
      
    for (uint8_t regAddr = 1; regAddr <= 0x0F; regAddr++)
      {
      
        SPI.transfer(regAddr & 0x7F); // send address + r/w bit
        regVal = SPI.transfer(0);
        

        Serial.print(regAddr, HEX);
        Serial.print(" - ");
        Serial.print(regVal,HEX);
        Serial.print(" - ");
        Serial.println(regVal,BIN);
      }

      digitalWrite(10, HIGH);           // set the SS pin HIGH
     }




    27Mhz - Radio Ideas - Page 4 Ax5043_001

    Regards
    Jonathan _._

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    david f
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Wed May 11, 2022 9:19 am

    Fantastic result!
    I will try again with exactly that software.
    Once they start talking it can take off!
    Well done!
    David
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Wed May 11, 2022 12:29 pm

    Thanks again. I can confirm that the chips give the same result at my end

    27Mhz - Radio Ideas - Page 4 2022-015

    I don't actually know what went wrong with my earlier tests. Having the SPI test software means that I can do basic tests on the chips.

    I have just tried them all with the same results above. However one chip gave the result below.

    27Mhz - Radio Ideas - Page 4 2022-014

    This one also doesn't give out any RF output. It presumably is a fault with my soldering. I wonder if I was unlucky and this was the one I tried the tests on?

    David
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Wed Jul 20, 2022 4:04 pm

    Just some feedback on this (long-term!) project:

    https://github.com/rdforrest/27MHz-using-AX5043

    Very puzzling but TX circuit does not seem to transmit on full power. I am not quite sure if this is hardware or software. (The module current is about 2mA, but should be about 50mA from data sheet.)

    It's slow progress on this project - still not sent any data or transmitted at usable power. But it is very interesting to delve into. Beats Sudoku!

    Any suggestions most welcome!

    David
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    geofrancis


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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  geofrancis Mon Jul 25, 2022 3:20 pm

    https://github.com/pascallanger/DIY-Multiprotocol-TX-Module/discussions/711#discussioncomment-3222101

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    C-3PO
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  C-3PO Mon Jul 25, 2022 3:45 pm

    Hi David,

    Have you set TX register TXPWRCOEFFB?

    I think this is register number'ish

    169 TXPWRCOEFFA0
    16A TXPWRCOEFFB1

    What are these reigters set to?

    Regards
    Jonathan

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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Mon Jul 25, 2022 6:25 pm

    Hi Jonathan ,
    16A is set to 40 and 16B is set to 96. ( As per "Ax5043 not Black Magic " instructions.
    David
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Sat Aug 13, 2022 12:15 pm

    This looks very interesting. Rob Schuckman has been using an AX5043 successfully for underwater communication.

    https://www.electronicsworld.co.uk/building-and-evaluating-an-underwater-rf-communications-link/33705/

    Does anyone know how he can be contacted? I have found his LinkedIn profile but it is all in Dutch and I have never joined LinkedIn.

    David
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  C-3PO Sat Aug 13, 2022 4:21 pm

    Contact form on bottom of his website home page

    https://www.robschuckman.nl/

    Regards
    Jonathan

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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Mon Aug 15, 2022 2:59 pm

    Thanks, Jonathan.

    I have sent Rob a message and a link to this forum. (I suggested that the ability to transmit through the air/water interface at 27MHz was more important to us than transmission through water. I also suggested that the use of 27MHz for radio control could be a worldwide market for someone (him?)

    David
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  C-3PO Tue Aug 16, 2022 7:50 am

    Hi David,

    Have you seen this resource

    https://gitlab.com/librespacefoundation/ax5043-driver

    And this appears to be a full tx/Rx example @ UHF

    https://github.com/alanbjohnston/CubeSatSim/blob/master/afsk/ax5043.h

    Regards
    Jonathan

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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Wed Aug 17, 2022 9:59 am

    Thanks for the information, Jonathan.

    The first reference an "OS-independent implementation for the AX5043" looks interesting but I don't think I have the depth of knowledge ( I am just a keen amateur) to make use of it. Will it develop into something which we can use easily?

    The second one also looked promising and I tried it on a Raspberry 4. As usual with all the AX5043 C programs I have tried on the Raspberry I couldn't get it to compile! I don't have much knowledge of the Raspberry and I'm using Visual Code as an editor I have had a little more success using AX5043 Python routines using the Thonny IDE but still without getting the AX5043 to run.

    It is very slow progress on this project.  I have still not sent any data or transmitted at usable power.

    I am still not sure that I have the hardware working properly. (AX5043 connections and RF filter.) The low current draw indicates a problem. The AX5043 oscillator does function at 16MHz but any RF I have picked up on my SDR may just be harmonics.

    However I'm sure that a simple Arduino based approach is right for our r/c model submarine application. (Need for small size and low power. The Raspberry Pi doesn't really fit the bill.)

    If anyone else would like breakout boards suitable for the AX5043 (I also have two boards with AX5043 chips already mounted by me) I can let you have them for free as long as you let us know how you are getting on with them on this Forum. (Please PM me if you would like boards.)

    David

    P.S I have had a reply from Rob and he will reply in full shortly.

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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Mon Aug 22, 2022 10:02 am

    Rob phoned me last Wednesday night.

    He was very helpful and wanted to see how he could help.

    He stressed that he was primarily developing methods of underwater communication for high data rates within water i.e no air/water interface. So this was somewhat different from our radio control application which he was interested to find out more about. I mentioned the need for low(ish!) costs and the use of existing transmitters probably using the trainer plug (ppm) signal.

    He has already developed a working board using the AX5043 at 27MHz but he thought that  these were probably more complex and expensive (and maybe physically larger?) than the sort of board we needed.

    He suggested that an RF front end using an AX5043 could be the way to go and he will put together an outline specification.

    He wanted to say that he was interested in submersibles and model submarines but all the work he was doing was in his own personal time. He was interested to hear about other Associations - the SubCommittee and Sonar-ev.de, in particular. (He lives in Holland, I think. His English is perfect!)

    David

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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Wed Sep 28, 2022 4:01 pm

    Hi,

    CALLING ALL US MODELLERS?

    As a humble Brit, can you confirm that these links summarize the available R/C channels for you in the States?

    https://www.fcc.gov/wireless/bureau-divisions/mobility-division/radio-control-radio-service-rcrs

    https://www.law.cornell.edu/cfr/text/47/part-95/subpart-C

    In particular, does anyone in the US actually use the 27MHz channels and are CB radio enthusiasts still active in the States? (They are more or less defunct over here.)

    David
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    tsenecal
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  tsenecal Wed Sep 28, 2022 5:53 pm

    a better list of available frequencies.

    https://www.liveabout.com/radio-frequencies-in-the-us-for-radio-controlled-vehicles-2862530

    the 50mhz frequencies require a HAM technicians license for legal use.

    the 72mhz frequencies are reserved for aircraft use only
    the 75mhz frequencies are reserved for ground use only

    the rest are shared


    not listed are the 433mhz and 915mhz frequencies, 433mhz also requires a HAM tech license.


    Last edited by tsenecal on Wed Sep 28, 2022 5:56 pm; edited 1 time in total

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    Post  tsenecal Wed Sep 28, 2022 5:55 pm

    as to CB use here in the states... I don't know of anyone that still uses them, but that is just me. i am not a long haul trucker, so i have no idea if they are still used in that situation.

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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  david f Fri Dec 02, 2022 2:53 pm

    Bad news!
    I've just got back from holiday to find that the AX5043 radio transceiver chip and its variants are going to be discontinued for manufacture.
    I've been in touch with Rob in Holland who confirms that this will prevent any larger scale commercial manufacture.
    It is a shame because this seems to be the only modern chip which can work down to 27MHz. The only alternatives will be earlier types of hardware with coils etc and all rather "home-brewed"!
    So yet again we have a lot of development work wasted and no way ahead for 27MHz - which IS a useful frequency for r/c model subs.
    So our UK/US options are still second  hand 40/75MHz or home built 433/458MHz or 915/868 MHz or 2.4GHz with exposed antenna.

    David
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    Last edited by david f on Tue Dec 06, 2022 7:38 am; edited 1 time in total
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    27Mhz - Radio Ideas - Page 4 Empty Re: 27Mhz - Radio Ideas

    Post  Marylandradiosailor Tue Dec 06, 2022 2:18 am

    Yes, that's not good news on the AX5043, I had been considering playing around with it sometime.

    I use 75MHZ or 6 meter band amateur for control but I really want a full telemetry link and have been testing 27Mhz (and probably 6 meter in the future) for a telemetry link with good results so far, the FCC permits limited telemetry on the 27MHz band. So far I have been using modified standard 27MHz rc components from ebay (internally modified for a microcontroller interface) but over this winter I am planning to build some new boards that will handle either 27MHz or 6M. I have been looking at the TI LMX2571 for the FSK transmitter among others .... I'll be releasing everything as open source when done.

    Great to see this type of technical discussions on this forum, Khim

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