Everything Robotics…….and then some

All the design files and software are now available online for Jan Gentschs M8 Triggr Implementation.

Files can be found here.

IMG_8198.JPG, originally uploaded by jgentsch.

The first StrobIt Triggr seen in the Wild!

Jan has made a neat and well packaged version of the StrobIt Triggr. Based on the AtMega8 it runs from a single AA battery. Well done Jan!!!

Ok I have finally had a little bit of time to work on things (will be short lived as I’ve just bought a house and moving in the next couple of weeks Aghh!!).

Things are getting very close to reality after many design changes, the very nearly final Strobit Trigger base board, aka a modified Ardiuno BT board, with the Bluetooth removed and now fitted with the RFM12B SMD Tranceiver module and an external SMA antenna connector. The Eagle 3D side of things still needs work as some components are not shown and the inductor for the DC-DC converter is incorrect, but you get the basic idea right!

Why have I gone to a non-dedicated trigger board?

Well a couple of reasons, initially to cover myself from any patent issues that might have arrisen had I used a dedicated wireless triggering device, but mainly to allow better expandability. Why have a dedicated trigger with all the fruit and only use half of it, this way dedicated boards can be used, i.e. standard trigger, or sound/light trigger, sequences etc. Another reason is that the Ardruino is very well established and supported in the open source community, especially when it comes to the firmware libraries etc, it’s already been done. also I can use these in my robotics hobby as well, not just for photography.

Ok onto the board features:

• Fairly compact same size as ArduinoBT
• Standard Arduino Pin headers, so should be able to use with existing shields.
• Will operate from as low as 1.2V, so should work from x1 NIMH AA easily enough.
• RFM12 Tranceiver, up to 300m range (as per datasheets, although it does depend on the datarate)
• SMA connector so you can connect an external antenna for better reliability and range, or remove the SMA connector and use a piece of wire as the antenna.

What is left to do?

• Well the design is pretty well done, I want to get some prototypes made so I will be sending it off very shortly for fabrication.
• Different variations of shields need to be done, first one being stock standard strobe type of triggr, input and outputs, then others as needed

I was surprised when I looked at my blog today how long ago my last post was, nearly a month ago…bugger where has the time gone - it’s nearly christmas again LOL!  Way overdue for an update I think.

Well I can tell you where the time has gone, mainly sourcing component suppliers and getting prices in for the Triggr boards, not to mention a redesign.

Have had a delay also with the design, which really was a lawyer thing.  After speaking with a few people and my laywer about some issues initially raised on the forums about the existing patent held by the Pocket Wizard People, I’ve decided to make some fairly significant changes to the design, All the functionality is still there and its still expandable, actually probably more expandable than it was before.  I just needed to make it a non-dedicated remote camera trigger, in fact it’s not really a trigger at all, confused? well all will be revealed

In short these changes have been made but I need to finish the new PCB, which I’m hoping to finish this week, and then get some prototypes underway, hopefully I will get a 3-D model of it in it’s current form on this site as soon as I work out how to use Eagle 3D.

Most of the prices are in although I’ve not calculated the price based on the new design, it is still looking good, the biggest killer so far is freight.   When you can get resistors at $0.0016 each in reel of 4000, it doesn’t work out to be that expensive, however at freight of AUD$45+  it all starts adding up when you are needing different reels of capacitors resistors from different suppliers etc.  So…..at the moment in between finalizing the new Atmega Board design and my real day job, I’m sourcing a turnkey supplier and assembly so that I only need to pay freight once.

As a side note looks like best price breaks start at 1000 units for most things so I need to make sure I do my numbers correctly so I don’t end up with alot of expensive paperweights that I can’t get rid off LOL.

I’ve created a page for the trigger project and have just updated it all about the prototype and testing etc.  Over the next few days I’ll be posting source, photos etc

Found here - http://blog.everythingrobotics.com/strobit

Well I finished the two prototype boards tonight with some minor changes and a bit of troubleshooting, still lots to do though.  I now have them triggering.  Will be testing further over the next few days to get indication of range etc.  So far it is only syncing at 1/100.  I will be posting more details , schematics, firmware etc as well as I get time.

After a hectic and very hot Christmas (41DegC) I managed to get some development time and finished 2 prototype boards.  My RFM12 header boards still have not arrived, caught up in the christmas mail I guess :(  So I’ve had to resort to hand soldering some wires to the header in the meantime. (Murphys law suggests that as soon as I finish soldering these headers the breakout boards will arrive in the mail)

Tomorrow/Later tonight I will test both of them and see if I can get a remote trigger happening woohoo.

Sorry about the quality of the photos as they were taken with my phone

I’m pleased to announce the very ALPHA release of the RFM12 library for the wireless HopeRF RFM12 FSK tranceiver module that I’m using for the strobist open trigger project.  It was developed under BOOSTC for the PIC embedded controller, but should be easily ported to any compiler.

Most of it is untested, hence the alpha release, but it’s a good starting point.  Everything is fairly well documented, but like any project could do with more.   Please send me any bug fixes/improvements that you may find while using it.

Download:  rfm12-0_1a.zip 

Features:

• 433Mhz and 915Mhz HopeRF FSK RFM12 modules supported
• Initialisation with a basic config
• Set Frequency
• Set Receiver Bandwidth
• Set Receiver Gain
• Set Receiver Signal Strength Indicator Level (RSSI)
• Set Transmit Power level
• Set Transmit Modulation
• Set Baud rate
• Enable/Disable Transmitter
• Enable/Disable Receiver
• Transmit a single byte - blocking
• Transmit a buffer of data - blocking
• Receive single byte - blocking with timeout
• Receive ‘x’ number of bytes into buffer - blocking with timout

 TODO:  (not in any order)

• Testing
• Howto documentation
• RFM12 Interrupt handling 
• Non-blocking Tx/Rx routines
• MSSP SPI implementation (current SPI implemented via bit bang)
• Frequency hopping
• Custom configurations

License:

Released under the Creative Commons - Attribution-Noncommercial-Share Alike

Disclaimer:

Please use this library at your own risk.  I will not be held liable for any damages.

I finally had some time this weekend so I started the hardware verification, mainly getting the PIC and the RFM talking together via SPI, of which I have had no previous experience.  The PIC is receiving it’s clock source from the RFM12 via the CLK pin so I dont need any external Xtals.  The RFM12 default clock rate on reset is 1MHz, so the first challenge is to change the speed of the RFM12 CLK to 10MHz, that way I know the PIC and RFM12 are talking.

 As I’m doing most of my software development with BoostC (http://www.boostc.com), there is a library to use the on-chip MSSP (SPI and I2C) functions of the PIC16f873A, so I thought I’d use this and the on-board SPI functions to handle all SPI communications to the RFM12, after a very frustrating few hours and with my scope monitoring the SPI pins, I finally got the SPI to spit out proper CLK, SDO, and receiving something back on the SDI line after I realised I had not had my interrupts enabled to allow for the non blocking SPI functions DOH!

Now that something was getting out and back in, however none of the commands I sent seem to be getting through, well at least not interpreted as commands by the RFM12.  After much head scratching and re-reading of the RFM12 SPI timing diagrams It occurred to me that the 16bits that make up the the RFM12 commands were getting send through in byte sized chunks, i.e. 8 bits at a time were being sent through, then the next 8 bits were send with a delay in between the two bytes, this makes sense as the internal SPI uses an 8 bit register that gets transmitted, although the library I was using allows from the transmit of any number of bytes via a buffer.  I figured this was the problem and quickly wrote some bit banging SPI functions to test the theory, and straight away the RFM12 responded to my commands and now I have the PIC running at 10MHz.

So now that  all is working in the land of Oz as far as my PIC and RFM12 and talking to each other it’s onto finishing the RFM12 library I started last week and testing that with the RFM12 Demo board so I can test Tx and Rx functionality without having two development boards set up.

As mentioned in my last entry I was toying with the idea of frequency hopping on the RF side of things, well looks like someone has implemented something similar here http://www.raccoonrezcats.com/rfmodem.html I’ll like to do something similar to this as it seems doable. 

While not able to get some “hands on” development time over the weekend, I did more reading of the HopeRF modules and these will be able to achieve the hopping, as the can programmed to any frequency in the 902-928Mhz Freq range so definately looking achievable.

If what the above links says on the site then we could (at least in theory) have a max output of 1watt if we chose to implement hopping, else we are limited to 1mW output power.

Trying to fit the functionality into the existing ebay trigger receiver housing seems to be a royal pain in the butt, especially trying to work in with the batteries, so after a few days of PCB redesigns and juggling compments around I have put that particular design on hold and moved forward with my original PIC16F873A design, also I did not like the fact that there was 2 circuits to maintain, a transmitter and receiver, this then leads me to the next problem.  I want something easy for the end user, something similar to the Pocket Wizard Plus that is really a no brainer for the user to drive, i.e. a switch to select operation mode and channels, a 3 and 4 way slide switch respectivly, well do you think I can source any 4 way slide switches easily?  Seems I can get some 3 way easily enough, and I guess I could use a rotary switch but these are too clunky for my liking, but still an option.

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A couple of design changes,  main one being I could not physically fit a single design into the existing housings that would encompass the Tx and RX, the RX housing is the problem as it’s a fairly small board so that means I’ve had to change the processor so that I can physically fit everything as well as the RF onto the board, so now a single design using the PIC 16F873A now becomes 2 circuits, Tx and Rx using a PIC16F88 as the MPU.

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Things seem to have slowed down on the forums qute a bit, I’ve also put a poll up for the project name, based on a few from the marketing topic where a number of people have put forward their suggestions, well, while the poll has been viewed a large number, only 12 people have voted so far, a bit dissapointing, obviously they didn’t like the names I’ve pulled from the forums, Oh well I know you can’t please everyone.

Anyway moving forward….I’ve been busy researching RF modules and coming up with a prototype design.  Currently I have 2 prototypes designs on the go.   One as a drop in board replacement for the Ebay Triggers based on the RFPIC, the other as a Pocket Wizard type trigger, but hackable, based on the Phillips LPC2148 ARM7 Chip.  The designs are not complete by any means.  I’m still in 2 minds about the RFPIC Design I may for go it in favour of a standard pic with an external RF module, that way I could use the same RF module in both designs.

 Ebay Trigger Replacement Preliminary Design (TX)(PDF)

 LPC2148 Based Trigger (PW Replacement) (PDF)