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Messages - RichF

2
Breakout boards / Re: ATX Breakout board
If you don't have a PSU,lying around this is a good deal for persons in the USA

Today only. Newegg has the Antec High Current Gamer Series HCG-400 400W ATX Power Supply for $59.99 - 15% off promo code EMCNBHG22 - exclusive $40 rebate = $10.99 with free shipping. Features: 80 PLUS Bronze Certified, Single +12V Rail, Active PFC. NEWEGG  http://www.newegg.com/Product/Product.a ... 66e1614afd
4
General discussion / Re: Cheap components - TaoBao
[quote author="matseng"]
The shopkeepers normally don't ship overseas and only accepts local payment, so you need to use an agent to make your purchases. You add the url's of the items you want to purchase at the agents website. [/quote]

Can you recommend an agent for USA buyers?
5
Project development, ideas, and suggestions / Re: Long distance wired data comms
I have work in industrial environments for many years,  I would definitively recommend  rs485, either half/full duplex ,with shielded, low capacitance, twisted pair cable..  Remember ONLY connect the shield at the source.    Although adding a CRC check is preferable , as long as you are not doing any control actions  a check sum security code is most likely acceptable.  I suggest a protocol where the remote echos the transmission back to the host, it can also then tell the host, it has addition information to send.
6
Project development, ideas, and suggestions / Re: PCB Tools
Product Revision Notes
Version 5.71 Updates & Additions:
Corrected DC resistance error in metric mode.

Version 5.7 Updates & Additions:
Added a conductor crosstalk calculator.
Minor menu item changes.
7
Breakout boards / Re: ATX Breakout board
Another comment is that many, if not the majority, of the PSUs use simple L79xx regulators for the negative rails. These regulators are internally limited by spec'ed at  <2.5amps.  This will either be below the 1812@1.25a fuse's trip point or will take considerable time.
8
Breakout boards / Re: ATX Breakout board
I was looking at the photo of the breakout board on SEEED  along with the BOM listed in the  the documentation. Both imply that the same fuse (2amp??)  was used on all outputs.  The issue I see is that the -5v and -12v  are rated by the ATX power supply guidelines respectively at  .3  & .8amps    While the +12v, +5v & +3.3v capacity will vary based on the powers supplies total wattage capability, the -5v & -12v ratings are fixed at the previously stated levels.    My point being, using the same 2amp fuse for  -5v & -12v  provides no protection.
9
Project development, ideas, and suggestions / PCB Tools
Saturn PCB Design Inc has a free download (www.http://saturnpcb.com/pcb_toolkit.htm) of a very comprehensive toolkit.  If you are involved in PCB design I think it is a must have.  As the web site describes it:

Saturn PCB Design Toolkit Version 5.65 including the new IPC-2152 Update!
The Saturn PCB Toolkit is the best resource for PCB related calculations you can find.
It incorporates many features that PCB designers and engineers are in regular need of like current capacity of a PCB trace, via current, differential pairs and much more. Please download our PCB Toolkit today for free and enjoy!
10
Project logs / Re: Guess what it is and get a free PCB of it
a standalone programmer/debugger with Atmels PDI  interface  AD;for address, Da: for Data  Hex pad for data  Pc program counter?


[quote author="matseng"]This is the third iteration of the design.  I must admit that I haven't actually built the first two versions of it, but this is probably close to what I want.  The first two versions used the Mega644 + FT232 and Mega644+Mega8U2 but I went all in in this version and used the Xmega32/64 instead.

The Mega644 is a 20Mhz device and needs 5 volts to do that so I had to have a SMPS Boost converter on the PCB to get 5 volts from the Lipo.  The XMega series does 32MHz and is a 3.3 volt device so I just need a simple LDO to get power to it. The losses is not too bad going from 3.7 volts to 3.3 LDO - not much more than in the SMPS going from 3.7 to 5.0.
The Xmega also gives me onboard USB, same flash/ram and is >30% faster than the 644 and is also a bit cheaper.

The downside with the XMega is that it is a slightly different beast than the old Mega-series so it will take a bit to get used to it, but it's always good to challenge yourself and learn something new. Right?

This PCB is excactly the same size as a credit card and have the XMega, a Lipo battery and charger, a MicroUSB for comms and charging, a buttload of tactle switches and a bunch of 7-segment displays on it.  I'll tweak the design a bit more and then send the gerbers to Seeed and see if I can get it working.  Major parts of the firmware is already done for the 644 so it's about time to actually try it on some real hardware.

I'll send a PCB for free to the first person that correctly guesses what this project actually is meant to be.

-mats
[attachment=0][/quote]
11
USB Infrared Toy / Re: can i command my usb ir toy from an hyperterminal
[quote author="ian"]I think the problem is that you cannot send actual byte values from hyperterminal, only text - there is a huge difference. In that example I used Hercules which supports HEX input.
[/quote]
According to the manual:

Another useful HyperTerminal feature is the ability to send out any of the 256 possible RS-232 (ASCII) characters by using the numeric keypad. Make sure the "Num Lock" key is pressed. To do this, hold down the ALT key and enter the desired numbers. For instance, hold down the ALT key and enter the 1, 2, or 3 numbers needed (i.e.: 0 to 255), and then release the ALT key to send the single ASCII character.

Note: When dealing with Hex code the procedure varies. For example Hex 80 can't be sent by simply entering 80 on the numeric keyboard. If you enter 80 (with ALT) on the keypad, you'll send a "P" (which is Hex 50). Hex 80 is actually Decimal 128, and 128 should have been entered.

Numerical characters generated with the ALT key need to be specified in decimal values 0 through 255. For these complex strings, it would be a good idea to generate your keyboard actions on paper before typing them. Also keep in mind many devices will timeout and throw away part of your command string if you take too long to enter a command.
12
USB Infrared Toy / Re: Possible to turn a pc on?
Although using the USB to wake up from sleep is cleaner , not all system  work satisfactorily doing this.  A cold start simulation the power button is the only option.  I therefore suggest to following

Since the signal to "turn on " an ATX style power supply is a simple TTL compatible signal spec'ed as follows 
VIL, Input Low Voltage 0.0 V 0.8 V
IIL, Input Low Current (Vin = 0.4 V) -1.6 mA
VIH, Input High Voltage (Iin = -200 μA) 2.0 V
VIH open circuit, Iin = 0 5.25 V
A software  mod to drive this a spare pin should be straight forward .  To address Ian comment about no memory to record the remote codes  they would first have to be determined with a connection to a PC then hard codded in the firmware.

Power connection  and the spare pin can all obtain on the JP1 header.

So Yes, it is possible, but woulds take some programming. Along with wiring to the ATX power supply
15
Project development, ideas, and suggestions / Re: check gas (GPL) tank capacity
Have you considered using a load cell?  Weighing the tank is by far the safest and most accurate method.  I see relatively low cost cells on EBAY that can weigh 135 lbs.  Depending on your tank size you could build a platform supported with multiple legs. The load cell would be placed under one of them.  This way the capacity of the load cell would be multiplied  by the number of legs

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