good radio link device - Page 1
Forum section: electronics / projects

author: roboteux
author_rank: Contributor
timestamp: July 26, 2023, 01:26:23 pm
content: Hi,I'm using NRF24L01P dongle board, to create a radio link between a robot and its docking station.But on some board it work fine and on other the results are terrible. I loose a lot of data (or I receive them with CRC error I don't know).I've seen that there some non original chip, when you buy this kind of dongle. So that could be the root cause of my issue.So I'm looking for something better to create a radio link using SPI or UART.In the same environnement, I use RC car radio control, and they always work very well. But I prefer something easy to solder rather than to hack the remote control to send my data.Thanks for any help

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 27, 2023, 02:32:27 pm
content: There are indeed clones of the nRF24L01+ I bought a bunch of these modules years ago, and I got them to work, but after that they mostly ended up in some drawer. I really disliked those chips. Nordic put in some convoluted "pipe" idea, that is either to simple, or too complex for any situation you may want to use it in. On top of that I had weird issues with messages getting stuck in that pipe and then getting out after a reset.I guess the RFM95 and RFM96 (LoRa) chips are much better designs. They have for example a much better integrated signal strength meter, that can be used for either measuring antenna efficiency or for optimizing for low power consumption when battery powered.I also sort of liked the "Moteino modules". Not exactly "cheap", but affordable and with breadboard friendly PCB which have both a radio and a uC on board.https://lowpowerlab.com/guide/moteino/why-moteino/

author: roboteux
author_rank: Contributor
timestamp: July 28, 2023, 07:53:25 am
content: Thanks for that.I'll give them a look

author: roboteux
author_rank: Contributor
timestamp: July 28, 2023, 11:41:37 am
content: Are you using them in Lora mode, or in the 433MHz mode.I wonder if the Lora spec is bringing something usefull, and not more complexity.I'll try to investigate a bit more the Lora stuff.I've just realized, I want my stuff to be legal in Europe and in the USA.So either I've got something on 2.4GHz.Or I need something in 433MHz for Europe and 915MHz for USA

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 28, 2023, 12:44:45 pm
content: to help you best, we need to knowwhat data rate do you needcan you live with slow baud rate = longer link distance due to more narrow band, cant trick fundamental physic lawsdo you need one way or two ways ?live 2 way or time division ? rx tx ?hopping ? stealth ? or imune ?is diversity on RX side possible ? adding two antennas / receivers / rf switch and such will remove phase nulling = huge range improvementalso : lower frequency = longer range, just the way it is,line of sight is also a thing to handlemy record is 125km los range at 19200 baus, at 433MHz using MICRF506i also used diversity, special band pass filter, preamplifier HMC616 and RF switch AS186and 7Watt amp on the tx side, and a yagi with 10dbi gain on tx side,the rx side antennas was 1/4 wave dipols using wires.if you like to know more just google scherrer UHF RC system.it is a one way system, but the chips MICRF506 can do two way multiplexed

author: roboteux
author_rank: Contributor
timestamp: July 28, 2023, 12:55:33 pm
content: Hi,I need 2 way com.it can be half duplex.Slow bit rate is OK (mini 256bps), 9600bps would be top.I don't need a long distance. 10m is enough.But It's inside communication in warehouse or factory, so the environnement could be a bit noisy.I'm looking for a 2.4GHz system so I can use the same in Europe and US.And I need to connect it to my MCU (it's a PSOC5LP from infineon (ex cypress)). Sur UART interface, or SPI.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 28, 2023, 01:28:11 pm
content: ok super with the feedbackwhen your 2.4GHz link fail indoor at that type of short rangeit is not due to link power problem,but due to a few thingsthe most obvious is wifi and BT stuff jam your linkthe other one is reflections and phase nullingimagine you are in a room full of mirrors, and play with a flashlight,that is quite close to how 2.4GHz links works indoorall the time you get hit by a positive and a negative delayed phase = zero signal,that is why you see all those antennas on wifi routers,they simply switch between antennas all the time to pick up that usefull signal,so you need diversity.

author: roboteux
author_rank: Contributor
timestamp: July 28, 2023, 01:55:28 pm
content: I agree, it's not a power problem.But I suspect bad module or bad chip could also be an explanation, but I fully agree with the reflexion issue, and the jamming due to Wifi and BT.The things that gets me, is that I also use a RC toy car remote in the same place, it's also using 2.4GHz. and I've never had any issue with it.Also in the same place I do have wifi working and a BT connection is working (it's not on all the time).Something with multiple antenna could be a very good idea. But I haven't found anything to do a simple serial link that could provide the support for it.Also a module with a deported antenna could improve things, so I can make sure that I've got a direct line between the 2 antenna.