![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibLjSnVpNuHAuYer1R73PhZYzqdDmQw_R83_XK__vkCRnexoCwkAhSPuHNjqa8NM9B6GCvCzyOYuUD1v8PFJppfLiYl4oPpGQ1hZjN9tGX11BIxOC_jr5-yMOhvSN-BOCQZD-X5awBIOjN/s640/IMG_1039.JPG) |
SVT MMDVM first calls |
The Digital Voice ( DV ) for the ham radio have started a few years ago but to build a hotspot ( a tiny personal half duplex repeater ), you will need some pricey equipments like DVStick with AMBE-3000 vocoder and USB interface plugged into a Raspberry Pi with an Arduino Mega to drive the UHF transceiver.
It all started around Sept 2017 when the price of DMR radio was getting below RM1,000 and a few of us purchased a TYT MD-2017, one of the more popular DMR radio at that time.
Secondly, without a DV hotspot, having a DMR radio is kinda useless unless you are within the range of a DMR repeater in your area.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEir6hDHbDkzvBQ93-hp5VNT-qLm8N7wl7vqSJEda6sDBbX5Ezw94Zo4EY3fLfkXWvW7vlieES9egQtQPZA_KhFeIBtBWu6EBPenL0j1iFKZs73VEclt1ukIpy59boTvmLseSiKKtbgmD7E-/s400/IMG_0898.JPG) |
MMDVM G4KLX |
Thanks to Jonathan Naylor G4KLX ( https://github.com/g4klx/ ) (and many many people people) that created the MMDVM, a software that integrated multiple hardware ( teensy, Arduino DUE, STM32F1, STM32F4 ) and Raspberry Pi running pi-star ( https://www.pistar.uk/ ).
When I saw the hardware requirements, I noticed that I actually have ALL the hardware with me, STM32F103 red-pill, Raspberry Pi and they were also using a version of Arduino called stm32duino.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxzw3uVdiHKbBrlnWIAHEhGnPM5RbX5g2OiB0jT21vZfiZNM_m1DYRp_sQICejG0TfU3xAjd0e79_rGSg9Bi4MvJwz-9Jfsn8Oe8EE2uLKiSaGl8vGliul23q7_77YBihmdlnuUIiZV79z/s400/IMG_0901.JPG) |
A few STM32 red-pill I purchased previously |
The only missing piece was the UHF transceiver called RF7021SE module plus changing the TXCO to 14.7456Mhz. So I started doing my research on different board designs and immediately design a single board layer to test out my design.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid1od3ViA3t-FCgpcQLmT4w2Lh7gQ4-R9aWQWuQLRRkH2yBm0geI_SAWcxwcBiynOXcv8e3eGDhWfg3NSiyvt-HwL5utYto01X90WynGCCegRlLS06y8biyHpMzrd8BKb23iZyNtCxYBZE/s320/IMG_0904.JPG) |
MMDVM boards |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZquUInSNTyDb_JyTIHfLv8kNVeC3AGQzxE8gaNjZJmZb9U5HknQ1UrIPRnrwrB296Xz0HxcdzNCnhdnPXaG6FDj0ZXbD9bzxfVKA-k17egx-0c33YlAImJ_xeDTQPlwVCbsXbS8pjtTTi/s400/IMG_0905.JPG) |
MMDVM boards |
Here is the first version after many iterations and because it was a single layer board, I had to place the SMD LED at the bottom of the board.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLC6paXc5R-pymQPoWEpmi-WLoi6V2Jv0s-8js6Ld1O18KWJuSg-ndY5PUMnuui0Z1PrKe82xTfysZViGEy-mB9d6radW9jhQhJ4xuIZ80rSmHfh41KzOsAAL92Wdn1e_hxP_2o3KpMMJ9/s400/IMG_0942.JPG) |
SVT MMDVM |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE_adwmWNAMPcMHhCDrhsMiRuZ85MYvvVdu7X3PXsSmFM-OltKQldPsxCgsD9ERGslaPSWx9JKZou1YY_8TdoyFOwEMF_7Q4VrhNtXxII5Sflayh63peg-n0fxHylv0aDbsWQrnhWEhgj6/s400/IMG_0944.JPG) |
SVT MMDVM 3D view |
Once my designed was almost finalised, I bring it to Uncle Chow ( 9M2CF ) to convert my PCB design to a single layer PCB.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiALkUp-12599MkDnaaxcDf10YNO_Ca8DG6R2ji77fkiYntBj_IR1NgPnkN2Gmc4p5RPqocLWmKxZqBCIjWxfcveFmlqo7V4jBbVrzktobuo6J_9U2Ow-6G_HH2ZWRQiov15_NIYZ9OPtwJ/s400/IMG_0948.JPG) |
SVT MMDVM negative |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKQGVEEN9Mujyy_kh9FW-jV_kuAYCEYz65GceXUZY9YgOICaE-2DRRvRQFM3kiNd46QvAkwNTD8oHes3HcL6rrJBglsQJGrSbrkPK-f3NS6U86VlXmr9_QpfH8aVgNns3yxBR2GgCeMUGk/s400/IMG_0953.JPG) |
SVT MMDVM etched |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3hrUs4GT3AbVDPJ62FD5UueyVkptn6Sas35j_0jce9-TNnQEy__ZFaZ7qSKpeeYVyiuH_w2Vjt3OuPDRcQsPuFRBjGbTcCRcU_odUTNe197mJOWkPaSsmVRaEMSRozHq9p8GN0KNz6Fjh/s400/IMG_0959.JPG) |
SVT MMDVM copper removed |
After some UV exposure and chemical baths, I got the SVT MMDVM board ready to be soldered.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgl8P3n1pIJ74Mqo7UMb4iPjN7r_OSCStKNXQPIOvhO9h0CmL0BgMxQxBH5DGdi7dpDPi7Egadxg4cWoK630WhgB72JfqhR-2iFJ1Y2tG2bXVpllFoSQMPqNwymniYFfaY6erKem_kNlCza/s400/IMG_0962.JPG) |
SVT MMDVM fully soldered |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgVCfs66WQVVrsHlF46IBS-p48Ya1awJ5ZMT3w9dNeFDzg2W7REc_0m0UQSqOgOK5nnZvKEBKgfGUkg5JRKMQdfhKn6vMwHExtZqKWnDNVnO38mENZZRzMqzV90T0B3dKJ0KNGnAY6JJq1/s400/IMG_0967.JPG) |
SVT MMDVM top side with red-pill |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEjt5AZ5e_gkbt10sd2SelznADGrsv5whIFLh-whpGA3m5DUlXEVmISQy006jc30sx4Nb9HJlnnytFwHgOw97Yfe3IIMJkhzp_ghPLDd6HCg0x26JUIgW7Jfxx5ZIxgwSl4TNhmOB_Pm75/s400/IMG_0968.JPG) |
SVT MMDVM running |
Fully connected to the RPI 1 and pi-star software loaded.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIq5BtAUbwBQzbHZjbQAHTCvA5TsYXnkJwyF1iQMN3haNI7MnzFPfB0xxEeS14Nb5ltPkEah9u7Hb2pqu8OXtG822hTng-_gIKBz82Ib4neGimHrJiXiqp9VD_9lm0YF6OwXUbg_MdU-6K/s400/IMG_0972.JPG) |
SVT MMDVM connected to RPI 1 |
Hi Bro, I've PM you on FB trying to learn more on DMR and MMDVM hot-spot but could not really understand it. I've purchased a dmr by anytone few days back.hope you can help me understand it better and to have a hotpot at home.
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