Comments on: How-to: Bus Pirate v1, improved universal serial interface

By: Ian Lesnet

Ian Lesnet — Thu, 12 Mar 2009 16:35:16 +0000

Sure, you can use a jumper wire to connect to either the 3.3 or 5.0 volt supply.

We did this in case we want to work with external supplies or low voltage parts, such as 1.8 or 2.5 volt parts.

By: Vaidas

Vaidas — Thu, 12 Mar 2009 16:24:15 +0000

oh, for pull ups need external voltage. Can i use VCC (3.3V) voltage from bus pirate?
Thanks, ian lesnet.

By: Ian Lesnet

Ian Lesnet — Thu, 12 Mar 2009 16:08:55 +0000

With pull-ups, TRIS=1,PORT=0 is HIGH; TRIS=0, PORT=0 is LOW. With a high-impedance bus like I2C we manipulate the TRIS (direction) register rather than the port pins. We've done a ton of testing of the I2C library, I'm pretty sure there's no functional problems. What are you trying to interface? Did you connect the pull-up jumpers and connect a power source to the pull-up supply terminal? What happens when you try menu option 'V'? 'V' will give you a voltage report. It should look like this if there is power to the pull-up supply terminal: VOLTAGE MONITOR: 5V: 4.9 | 3.3V: 3.3 | VPULLUP: 4.9 |

By: Vaidas

Vaidas — Thu, 12 Mar 2009 15:56:57 +0000

Oh, my in programmer soft (beeprog) need to select “program config bits” – i forgot about it.

Yes, i use pullups.
Maybe problem is in source file “m_i2c_1.c”, function “i2csendbyte” is line “SDA_TRIS=I2CHIGH;”? This command set SDA pin direction to input. but here need set SDA pin to high value – send “1″. When sending “0″, all ok – SDA direction is input, SDA value “0″.

By: Ian Lesnet

Ian Lesnet — Thu, 12 Mar 2009 08:37:38 +0000

Yes, 4x PLL is enabled in the firmware.

I2C is open collector, are you using pull-up resistors? I2C will always be low without pull-up resistors.

By: Vaidas

Vaidas — Thu, 12 Mar 2009 08:13:19 +0000

Thanks, ian lesnet. I only download original hex to my pic flash. 4x fuse is enabled in this hex, or i need enable it manually?

Now i use modified firmware and have 115200 speed (modify UART settings), but I2C mode don’t work. SCL, SDA pins allways are low. In terminal i write M, then 4 to select I2C mode, then { symbol and then trying to send 69 value (E symbol). Maybe i forgot something in mode selecting, or, like in UART enable with { symbol.

By: Ian Lesnet

Ian Lesnet — Thu, 12 Mar 2009 07:08:03 +0000

@vaidas – Did you disable the 4x PLL fuse? That might do it, as 28800bps isn’t a programmed speed option. It is set in the firmware, so check that your programing software isn’t making any changes.

We used software I2C because the I2C hardware module in the 24FJ64GA002 revision 3 is broken.

By: Vaidas

Vaidas — Thu, 12 Mar 2009 05:42:36 +0000

My bus pirate v1 default boud rate is 115200/4=28800 bps. Maybe i don’t program something, like fuses in avr?
And why bus pirate use software I2C, not hardware? I dont now why, but in my bus pirate I2C don’t work.

By: Ian Lesnet

Ian Lesnet — Wed, 11 Mar 2009 18:03:52 +0000

@sideblazs – The only way to do that right now is to make 9600 the default speed in the firmware and do a custom compile.

I don’t know if this helps, but today I tested V1a hardware (this how-to) with an FTDI-based USB->serial converter at 115200. I didn’t have any problems. I did have to go to advanced settings in the control panel and change the FTDI driver to 115200bps, the default was 9600.

By: sideblazs

sideblazs — Wed, 11 Mar 2009 17:47:37 +0000

@ian – re: problems with usb to serial adaptor

Sorry for the delay in responding. As you suggested I tried changing the bus rate to 9600 and the device now works via the usb serial adaptor. How do I make this change permanent?
When I unplug the power the bit rate reverts back to the non-working 115200 rate

By: Ian Lesnet

Ian Lesnet — Tue, 10 Mar 2009 19:02:01 +0000

Google's SVN access instructions don't seem to work. We use TortoiseSVN to access the repository. This is the correct URL for anonymous SVN access: http://the-bus-pirate.googlecode.com/svn/trunk/ Note that it doesn't have the trailing junk included in Google's instructions.

By: Ian Lesnet

Ian Lesnet — Mon, 09 Mar 2009 19:57:15 +0000

One LED is power. The other is OFF if the pins are in the safe Hi-Z mode, and ON if a mode is set and the pins are active.

By: Alessandro

Alessandro — Mon, 09 Mar 2009 19:50:11 +0000

WOW IT WORK!!!! :-) Finally!!!
Can somebody explain me wich are the behaviuor of the two led?
Because I have one bus pirate whit the led1 turned on on power on, and the other with the same led off. Wich is correct? When they light up and what they mean?

Many thanks again!!!!

By: Alessandro

Alessandro — Mon, 09 Mar 2009 19:36:13 +0000

@ ian lesnet
Finally I get my pic work whit the icd2 whit icsp. The problem was the icsp adaptor cable. The data about the rj11 of my icd2 clone pinout was incorrect!!!
Now the problem is to understand how use mplab to program the pic whit an already assembled program…

By: ultrasounder

ultrasounder — Sun, 08 Mar 2009 18:54:20 +0000

i am mulling over the concept of a FX2 based USB interface that gets straight jacketed to a 16 bit Micros. The data transfer speed being the one obvious reason, the other is I dont have to mess with generating 5V supplies. Does any one have a recommendation for a 16bit Micro?