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Thread: Arduino 433 modules for Picaxe

  1. #11
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    Quote Originally Posted by premelec View Post
    @doppler - I wonder if you find it hard to interface the PICAXEs to RF modules? if so what is different... thanks..
    I am very comfortable using the little 433Mhz (and 315Mhz) RF modules, using both straight serial and NKM2401 chips. This is also true for Sure Electronics 2.4Ghz modules, and Xbee modules. Those are simple serin/serout (or rfin/rfout) protocols. What would be hard for me is to come up with the SPI code for something as robust and feature rich as the RFM69 radios. I needed my data to travel 100m, with two barns (one metal, one concrete) in the line of sight, and then through the wall of my house. Even with a repeater on the corner of one barn, the 433Mhz modules just weren't powerful, or reliable enough. The 2.4Ghz radios have very limited penetration power.

    Using the LPL code with RFM69 radios gives effortless access to features such as Automatic Transmission Control (ATC), which dials down the transmit power to a minimum level for reliable communications, and very robust error correction (i.e., request for re-transmit on bad CRC) handling. The high-power RM69 radios have a range of a few miles in open air, and penetrate my obstacles with 100% reliability. You can set them to unique network and node ID's for isolated network communications on the same frequency.

    In short, it is a very easy to use, high power, reliable RF solution. To me it is the same as using a Xbee, but for cases where more power is needed. Just like I wouldn't want to try and develop an Xbee from scratch, I just want to plug-n-play an appropriate RF resource and move on.....

  2. #12
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    Quote Originally Posted by hippy View Post
    I think the best way to step round the 'is it PICAXE or is it promoting something else?' issue would be to post a link to an external web page which describes the thing rather than do that in detail here.
    Hippy, I thought I would post it under "User Projects - Communication", but I understand your concern. Thank you....., Greg

    ALSO: My apologies to 'friis' and all for hijacking this thread

  3. #13
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    Hi,
    Am I completely out of touch using the Drji modules?
    torben

  4. #14
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    Friis: It depends on what you intend! Aside from technical specs. (frequency, data rate, power, current drain, RSSI access,sensitivity, modulation schemes & error handling etc ) even "boring" aspects like module size, pin out spacing, budget, delivery time & supply voltage may influence choice. "Horses for courses " !!

    I've had a good deal to do with Dorji over the years, much of it PICAXE related. Most of my orders (as recently as March 2018) have been directly from their Shenzhen (China) base via their ever helpful Mark Yao. Mark then indicated that new LoRa modules, presumably using Semtech's SX126x new RF engine, were due for release about now.

    As far as I know, Dorji are still active retailers - a quick Google shows numerous products on their site. Here in NZ their "887" ASK receiver modules remain very popular educationally with diverse micros (RPi, PICAXE etc). Note - NZ & China have a free trade agreement which makes for extremely easy importing- we've no taxes levied on items valued under ~US$300 either.

    For duplex (2 way) 433 MHz work the budget & versatile HC-12 (not a Dorji product of course) admirably tends first choice. Rev. Ed may well want to favour it...

    Ruthless technical progress of course continues,with low supply (~3V) modules personally appealing. However the increasing abundance of small,smart & cheap rechargeable 3.6V-4.2V LiPo packs makes even that incidental!

    HopeRF's CMOSTEK RFIC based 433 MHz ASK receivers (below) tend favour for both low supply needs & their outstanding performance in marginal links. They seem to work with any 433 MHz ASK TX and UART capable micro -refer the Forum discussion from Nov. 2017.

    Stan.
    Attached Images Attached Images

  5. #15
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    Hi Manuka,
    I will try some of the new modules.
    Thank you.
    Incidentally, why does the receiver have two GND pins?
    torben

  6. #16
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    Yes - they're interesting (& CHEAP !) 433.92MHz ASK receivers. Module data here,with a 5V RFM210LH (below) & a seemingly more sensitive (at lower data rates) SPI configured RFM210LW versions here.

    With near throwaway prices and a mega competitive rapidly changing market,it's hard to credit that such hi-tech performance is worth bothering about for the makers !

    Duplicated GND pins are for RF ground & supply ground -for simple links just one can usually be used. Many 433 MHz RX modules have such duplicated (or even NC ) pins, which can come in handy when hacking them for the likes of RSSI taps. Back in 2014 I isolated a "spare" pin for RSSI use on a Spirit-On module (below) Stan.
    Attached Images Attached Images
    Last edited by manuka; 01-08-2018 at 01:20.

  7. #17
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    I'm a fan of the HC-12 transceivers: my preferred wireless module.

    I have also used the cheap ASK modules for one-way wireless links. I have found that there are two 'levels' of ASK receiver - check for a crystal on the receiver board like on Stan's attachment (Jaycar ZW3102) above. I have had far too many problems with misaligned, cheap receiver boards with LC (or RC?) tuning. Save yourself some grief and leave the crystal-less modules in the shop! No problems with the transmitter modules - all seem to have on-board crystals.

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