how to build a VEX programming module

[Eldarion]

Originally Posted by 1885.Blake

If I remember correctly, you have to send it the right pulse train.

I finally got it into programming mode by connecting the RTS/CTS signals to the serial port through a MAX232 converter. When I run a "Controller Verification" in the IFI loader, it thinks it is talking to an FRC controller ("Controller Verification Complete..." and "FRC" a little further to the right.)

However, when I try to actually download code, it goes through the CTS/RTS handshake, starts the Program LED blinking, and asks me to hit the (nonexistent) "Program" button on the FRC controller. An analysis with PortMon reveals that the IFI loader is sending six periods to the Vex controller, and expecting some kind of response. The Vex does not send any response, and the download fails.

Does anyone have any ideas on this? I am sooo close...

If I can get it working, I will be posting some kind of schematic and/or tutorial on how to build one of these things!

Thanks,

Eldarion

[Zak698]

One idea that i have come across while at work at Microchip is the idea of trying to use a Microchip PicKit2 Programing module, heres the link to it PICKIT2

.. njust an idea

[ltk]

You can use an in-circuit debugger to program both the master and user processors. You have to open the case to access the connector.

Using the pin designators on the silkscreen of the pc board, here is the pinout:

J1-17 PGD on the Master Processor
J1-18 MCLR on the Master Processor
J1-19 +5v
J1-20 no connect
J1-21 Port B7 and PGD on the User Processor
J1-22 MCLR on the User Processor
J1-23 RX2 on the Master Processor
J1-24 GND
J2-9 PGC on the Master Processor
J2-10 GND
J2-11 Port B6 and PGC on the User processor
J2-12 TX2 on the Master Processor

[I_Robot]

After following the directions posted previously in this thread, I managed to build a working programming cable. When using a usb-to-serial converter cable, they somehow mess up the handshaking that is going on to put the Vex microcontroller into programming mode. So to fix that, I had to use a microcontroller to generate the correct signal. So my home made programming module has a microcontroller in addition the the RS232 level shifter. You can take a look at the cable and a video of how it works on my site: www.CrestOak.com. Enjoy!

[n0rad]

Please can anyone share their working circuit diagram on how to interface the max232.

One thing that really puzzles me is where and how to connect the program button.

Thanks.

You can also email me at n0rad2002@yahoo.com.sg

Cheers

[bear24rw]

Originally Posted by I_Robot

After following the directions posted previously in this thread, I managed to build a working programming cable. When using a usb-to-serial converter cable, they somehow mess up the handshaking that is going on to put the Vex microcontroller into programming mode. So to fix that, I had to use a microcontroller to generate the correct signal. So my home made programming module has a microcontroller in addition the the RS232 level shifter. You can take a look at the cable and a video of how it works on my site: www.CrestOak.com. Enjoy!

Do you plan on sharing the schematic and source for your cable?

[I_Robot]

Originally Posted by bear24rw

Do you plan on sharing the schematic and source for your cable?

Unfortunately, at this time I don't plan on releasing the schematic and source. Right now I'm hoping to use up some of the extra parts I have in making complete cables. However, after that, I might spend the time to create a readable schematic and release the code.

[bear24rw]

Does the module put the controller into programming mode using the control lines?

[outpaddling]

Apparently so, but I'm not sure exactly how yet. Can someone explain what the handshake combination is?

I bought my son a VEX kit over the holidays, and wrote a VEX loader for *nix shortly afterward.

I made a serendipitous discovery that Mac OS X and Linux trigger programming mode by accident when the port is closed. (FreeBSD does not.) This happens reliably with both the USB/serial adapter and with a direct connection to the serial port on Linux. I'm using the orange programming module that came with the EasyC kit.

I can prevent it from happening by dropping RTS using an ioctl() call before the port is closed. Apparently OS X and Linux drop RTS when the port is closed, and this is *part* of the handshake to trigger programming mode. I have tried various combinations of dropping and raising RTS and other control lines, with no success turning on programming mode.

Thanks,

Jason

[popo308]

You just need to plug the RTS and CTS into a serial cable that plugs into the computer to successfully complete the handshake.

PIN_LAYOUT

[essence25]

Now if I have a rs232 to TTL converter that has the following pinouts:

GND
RX->
TX<-
VCC 3-5v

and I'm using a real RS232 pc port. Where do I Connect pins 4-CTS & 6-RTS from the vex programming port? The TTL converter does not have these...

Do I connect them directly to the serial port ? Does the TTL converter only need the TX/RX ports to go through it?

I dont use a USB to RS232.

thanks

[essence25]

What a useless and deceptive thread in regards to this programing button & cable. Funny thing is there is already a poster above selling this so called "Proprietary" cable for profit.. Way to go protecting the cable secret bs!

[Rick TYler]

Originally Posted by essence25

What a useless and deceptive thread in regards to this programing button & cable. Funny thing is there is already a poster above selling this so called "Proprietary" cable for profit.. Way to go protecting the cable secret bs!

Normally, I try to avoid this sort of post, but this one kind of set me off:

1) The thread includes the information you would need to make your own VEX programming cable. I don't think anyone is trying to be deceptive.

2) What cable secret? If you want to buy a factory-made and -supported part you can do so from IFI, and if you want to make your own, you can follow the information here.

There are better ways to communicate than through invective and imprecision. Perhaps you can more fully explain what you are trying to say?

[wrhsvex]

ya i know bringing back a dead thread
but can someone post some detail easy to understand pictures of how to make the VEX programming module please.
i will use USB to Serial Cable, RJ14 6-pin cable

[gblake]

Originally Posted by wrhsvex

ya i know bringing back a dead thread
but can someone post some detail easy to understand pictures of how to make the VEX programming module please.
i will use USB to Serial Cable, RJ14 6-pin cable

Originally Posted by I_Robot

Unfortunately, at this time I don't plan on releasing the schematic and source. Right now I'm hoping to use up some of the extra parts I have in making complete cables. However, after that, I might spend the time to create a readable schematic and release the code.

Based on what has been written earlier in this thread, the answer is almost certainly "No".

PS: It's not a dead thread - Don't let bullies convince you that tapping into existing information instead of splattering the net with constant ill-informed chatter is a bad thing. "Those who don't know history are destined to repeat it."