1
Messages
This section allows you to view all Messages made by this member. Note that you can only see Messages made in areas you currently have access to.
Messages - phophollety
2
Bus Pirate Development / Re: Poor Port Protectionb
Only a 47R series resistor and a clamp diode would be enough, I think it is not necessary to se the 74126 buffer as most tools uses, not becauses it does not works, but because can get the project more expensive, I do not know the BOM cost... but what about only 4 resistors and 4 clamps diodes? This will protect against short-circuit and reverse voltage....
The resistors are really important, in the past I experienced many IIC Tools being burned becuse the did not have any series protection resistor, only diodes clamps..
Are you planning any hardware interaction for the nexts months?
Regards,
Renan
3
Bus Pirate Development / Re: Poor Port Protectionb
4
Bus Pirate Development / Poor Port Protectionb
I'm very interested about buying and use the bus pirate, but before that, I was analyzing a bit the electrical schematic. Well, in my 3 years of electrical engineering experience, I learned one stuff "unprotected IOs gets burned - ALWAYS", soo I saw that there is no protection from the uC to the target connector, even 47R series resistor and a diode clamp, nothing!
Take a look about the bus pirate schematic.
There is no protection, working with development, is very very common to get the IOs in short-circuit, or to vdd, gnd or any unexpected situation.
This will damage the PIC easily.
I designed this interface before know the pirate bus (for my old company), the target protection hardware was designed for easy maintenance and to be resistent for the lab and to field..
Also, this hardware is compatible with 3v3 and 5v systems as you can change the pull-up voltage and pull-up individualy two lines (sda and scl ), diode clamp protection, high voltage reversed power and short circuit, about every thing that can happen in the development enviroment.
I realy would like to suggest this schematic as a hardware improvement for the bus pirate project, only few resistors, capacitors, two 74126 chips, and few fets transistors.
If you think is too much, take a look into the Renesas E8 debugger and the Microchip ICD2 debugger, they all uses this protection ( or part of ) and there are no problems with extras capacitantes or delays.
here, the schematic.
http://rapidshare.com/files/348875667/U ... e.pdf.html
Best regards!
5
Bus Pirate Support / Re: Why PIC24J64GA002?
Soo, I'm quite new about the project. Just got in on the way, surfing on hack-a-day pages.
I will keep my eye on it.
Is just a little bit funny but, I was looking for some USB platform with lot of protocols and those stuffs at work, I need to develop a debugging platform for our products ( just for dev use ) and this one, looks nice to me... I was in doubt about the PICKit Serial Analyzer Platform but, this one, looks nice and cheaper than the guys have used for years ( i2ctools.com ). Hope I can buy some of them to the company soon
6
Bus Pirate Support / Why PIC24J64GA002?
I would like to know what was the main cryteria of choice to choose the PIC24J64GA002?
I also like the microchip products and quality, but I asked myself: why not to choose another PIC24 with USB otg and eliminate the FTDI chip?