Poor Man's ERF/URF

erco

Senior Member
I'm all for wireless PicAxe programming, but the price of those URF/ERF modules has me looking for a more affordable alternative. I ordered a pair of these wireless modules for $10 to try: http://www.ebay.com/itm/321119672139?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Specs at http://www.inhaos.com/uploadfile/otherpic/UM-LC-1000-V10-EN.pdf

Looks to be a simple wireless RS232 serial port with a default 3-pin (S3M) connection: tx, rx, & ground at 9600 baud 8N1. Will still use a USB-Serial adapter to connect. Will advise after receiving.

Anyone else tried something similar?
 

Goeytex

Senior Member
I have 2 pair of these that I have yet to try out. Their other products that I have tested work fine. Wireless programming of Picaxe could be a challenge though. Maybe we can compare notes when I get around to testing these modules.

Goey
 

erco

Senior Member
Goey: Thanks, you're exactly the guy who I hoped would reply. Mine are at least a week away, so let's definitely talk more about this later to share findings & collaborate.
 

Technical

Technical Support
Staff member
Looks to be a simple wireless RS232 serial port with a default 3-pin (S3M) connection: tx, rx, & ground at 9600 baud 8N1. Will still use a USB-Serial adapter to connect. Will advise after receiving.
To wirelessly progranm PICAXE you need to be able to start/stop an RS232 break. The URF/ERF can do this, we are not aware of any other module that can, so we doubt these modules will work.
 

manuka

Senior Member
Is that just PICAXE wireless programming? What overall are you intending to do ?

These "inhaos" are not one I've played with before,but then they're a very new product. At US$10 + p&p they're not that cheap compared with barebones ERF/URF offerings. Is their ~3V supply able to be factored in? Mmm-their minimum data rate may be 9600 bps & config. looks a tad tedious...

Being 2.4GHz their range won't be more than a few 10s of metres of course, which naturally contrasts to many 433 MHz devices being good for 100s of metres. Is this likely to be an issue?

Please however let us (& Technical!) know your hands on impressions & just how you get on! Stan.
 

erco

Senior Member
@Stan: World domination and wireless PicAxe programming are my ultimate goals. Per technical, wireless programming may be difficult so I'll start with world domination. Twenty meters is plenty and there's free ship, so $10 flat is a bargain IMO for a shot at ruling the world.
 

Technical

Technical Support
Staff member
A wireless USB hub is hardly the same type of equipment as a low cost radio module. The hub should indeed work, as the serial comms will still be handled by the USB<>serial adapter you need to plug into it.
But its hardly small enough to build into a project! The only small size/low cost module that we know of that will work for PICAXE programming is the URF/ERF combo running the specially developed 'yellow dot' firmware.
 

erco

Senior Member
Size is relative; the hub obviously worked for that fellow's large robot project with plenty of room to spare.

Cheap new small wireless modules are coming out every week. Surely no one (including Rev Ed) has tried them all and can conclusively say nothing else will work. Let's use forum members' enthusiasm & resources to try some different ones and find one or more that work. Nothing wrong with that, right? Right?

Goey & me are interested, if no one else is. Maybe it's a Yank thing.
 

BeanieBots

Moderator
By all means please keep trying.
However, I've tried many different types and so far ONLY the URF/ERF modules have been able to do wireless programming.
For me it is the convenience of not having a lead plugged into my laptop. So far (besides the URF) the only thing that has worked is a wireless USB hub with the download cable attached to it.
 

Technical

Technical Support
Staff member
The solution is not trivial. The URF/ERF were extensively customised and developed by Ciseco specifically to support PICAXE programming. It is unlikely that any other low-cost wireless 'modules' will work without extensive modification.

To support PICAXE programming the wireless units must:
1) Support 4800 as the default baud rate
2) Support inverted polarity signals (idle low, active high)
3) Support RS232 'break' signal correctly (setting bit 6 of LCR (base register address + 3) high causes TX to be held inverted until bit6 is cleared again).

Point 1) is not normally an issue
Point 2) is sometimes supported, but can also be worked around with a simple inverter circuit.
However on almost all units point 3) is the problem, because wireless units do not normally even transmit the contents of LCR at all to the remote end, let alone correctly react to bit6 of the LCR.
 

Goeytex

Senior Member
I have finally tested the INHAOS LC-1000 modules. A pair of these makes a great wireless UART for around the house. However they do not support break signaling such as used by the Programming Editor.

When a long break such as used with the Picaxe Programming Editor to signal a program download, the module sees the break as a "0" , times out, and transmits a "0". So the Picaxe on the other end only sees a single byte "0" and will never enter programing mode.

If I really wanted to do wireless programming for a Picaxe with anything other than URF/ERF. I would probably try the DRF4432F20 or RFM22B, in which case FSK can be directly modulated by the serial data being input to the RFIC. With these modules you must add a Picaxe X2 & write the firmware. It can be somewhat challenging but is very doable.
 

erco

Senior Member
So much for the "Full duplex transparent serial port" in the item description!

Thanks for checking, Goeytex. I made one quick & dirty attempt to use them in their default settings without success. I was planning to delve deeper when I got more time, but now it appears that you have saved me the time. Sounds like you have considerable experience with wireless comms, so I will defer to your expertise.
 

Goeytex

Senior Member
For all practical purposes it does act as a full duplex serial port and does it quite nicely. The vast majority of applications will not require an RF module to support a "break" signal that is > 500ms.

One thing I noticed about these modules was that the Module's default local address (UID) did not match the address on the sticker. I had to write to the module and read out the data to get the correct local address.

Also, the local address can be changed by sending:
hserout 0, (checksum,save,$F0,$04,addr_0,addr_1,addr_2,addr_3,0,0,0,13,10)

But the address is not saved to EEPROM regardless of the value of the "save" byte. This is not mentioned in the datasheet. All other relevant parameters CAN be saved to EEPROM.
 

srnet

Senior Member
I would probably try the DRF4432F20 or RFM22B, in which case FSK can be directly modulated by the serial data being input to the RFIC. With these modules you must add a Picaxe X2 & write the firmware. It can be somewhat challenging but is very doable.
I have tried direct mode on the RFM22, you can have the RX data appear on one of the GPIO pins.

You can see the data, but its accompanied by a great deal of noise, especially when idle, in much the same way as you would expect for an OOK module.

If you get it working let me know.
 

Goeytex

Senior Member
If you get it working let me know.
Wireless programming of a Picaxe is not something I am particularly interested in. I see it as a clever trick with little practical use, so I am not going to spend any time trying to do it. I was just curious about the capabilities of the LC-1000 and hooked a pair up to a logic analyzer to seen how they would handle the Picaxe "break".
 

Goeytex

Senior Member
UPDATE:

I spoke too soon. While it may be of limited use to most ....

I have successfully set up a pair of LC-1000 modules for wireless programming of a Picaxe. Have not done extensive testing but so far about 50 downloads at a range of 50 feet without any errors.

If there is some interest in how to do this, I will do a write up in completed projects.

A pair of these modules cost about $10 US with free shipping. They work really well.
 

manuka

Senior Member
Very good work indeed - naturally there's some interest! How about we let "Oracle" win a couple more Am. Cup races in appreciation? Just a couple mind... Stan.
 

erco

Senior Member
Would LOVE to hear about it, Goeytex. I haven't touched my modules since your last update. Kudos for your achievement!
 

tony_g

Senior Member
UPDATE:

I spoke too soon. While it may be of limited use to most ....

I have successfully set up a pair of LC-1000 modules for wireless programming of a Picaxe. Have not done extensive testing but so far about 50 downloads at a range of 50 feet without any errors.

If there is some interest in how to do this, I will do a write up in completed projects.

A pair of these modules cost about $10 US with free shipping. They work really well.
+1 for interest as well, mine turned up today in the post.
 

Goeytex

Senior Member
I am testing various USB/TTL modules to see which one's will work. The issue as (I described in Post 13) is that the Lc-1000 cannot send a "break" across a wireless link. The other LC-1000 just sees a "0". So The break has to be "simulated" in firmware.

There are also other concerns with USB/TTL adapters. A very cheap Prolific adapter works good for wireless programming. I have programmed 08M2, 14M2,20M2 and 20X2 over a wireless link. However, for some reason a CP2102 and a Generic FTDI Adapter cause the LC-1000 to stop functioning after sending at the "break" to the LC-1000. Any of these adapters will work fine for a wireless UART, it's just the break thingy that I need to solve so that all USB/TTL adapters will work as long as they use 3.3v logic levels and can supply 3.3v @40ma. Once I get this solved I will post all the details.
 

Technical

Technical Support
Staff member
Try reduing the latency from the default 16 to 2 on the FTDI driver properties (right click in Device Manager)
However the usb stick version (LC-1000U) may be a much better solution if it could be made to work, as it would eliminate the adapter and soldering.
 

Goeytex

Senior Member
Good idea with the FTDI adapter. On my list of things to try. The LC-1000U stick uses a CP2102, but the CP2102 latency cannot be changed easily (if at all). If I can't get it to work with a LC1000 and a Generic CP2102 adapter then I doubt that the Lc-1000U will behave any differently.

The problem occurs after the Program Editor receives the Picaxe ID sequence (165,???) and sends the (170,0,0,?) to the LC-1000 to be transmitted to the remote LC-1000/Picaxe. With a CP2102 or an FTDI adapter, the LC-1000 does not transmit the 170,0,0, although it was applied to the LC-1000 TX pin. With a Prolific adapter it does fine. I am thinking that the time between the break signal going from low to high and the start of the next byte (170) is too short for the LC-1000 to handle. I think the break may need to be off (low) a couple of ms longer before the 170 is sent. I have no clue what the LC-1000 firmware is doing with a steady low on it's TXD pin and how long it may take to recover when the break is removed. l So am doing a mockup with a Picaxe simulating the Program Editor so that I can adjust the timing a bit and see if that is the problem.
 

Goeytex

Senior Member
Update:

Some other things`came up and I had to put this on hold for a while.

However with a few hours of experimenting I have come up with a fairly good solution using a pair of INHAOS LC-1000 RF modules for wireless Picaxe programming. The solution requires a Picaxe 14M2's to act as "firmware" between the LC-1000 module and the USB/TTL adapter on one side, and the Picaxe being programmed on the other side. This adds about $8.00 US to the cost. The LC-1000's are $10 a pair. And a Generic CP2102/PROLIFIC USB/TTL adapter is about $3.00 on Ebay, so that's about $21.00 US plus some resistors and a couple of cheap transistors . The 14M2's also include code for configuring the LC-1000 as well as baud rate detection and some bells & whistles for error trapping. It might could be done with a pair of 08M2's but that would requires sharing of I/O pins which I don't care much for when the 14M2 only costs an extra buck.

Right now I have the Program Editor open on a PC in the Lab and I am Programing a Picaxe 20M2 that is in the living room about 20 meters away.

Look for write up in the next few days.

Gowy
 
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