Sunday, July 19, 2015

Op-Amp cheatsheet?

Just found this old post at facebook. Cool!?

Opamp BasicsLike -> Microcontroller Projects & Updates
Posted by Microcontroller Projects & Updates on Thursday, July 4, 2013

Thursday, July 16, 2015

Arduino RFID, RC522, VUSB HID as Keyboard

Wrapped my project into nice grey project box. Nice project i have to combine
Arduino, RFID (RC522), VUsb together as HID Keyboard. Just tap an RFID card
and my little chips send it to computer as keyboard input. Warning this project not working
on Windows XP. And runs perfect on Linux OS, WinVista, Win7 and Win8.1

You will need to create a dir named *UsbDevice* in the arduino libraries,
this example taken from my Linux Debian8 64, yours may vary.
adesanto@debian8:/opt/AVR/arduino-1.6.9/libraries$ ls -ltha
total 6.1M
drwxr-xr-x 26 adesanto adesanto 4.0K Feb 12 00:49 .
drwxr-xr-x 12 adesanto adesanto 4.0K Feb 12 00:49 ..
drwxr-xr-x  3 adesanto adesanto 4.0K Feb 12 00:12 UsbDevice

And clone the code into the newly created dir. Then the 2 codes
below are good to be compiled.

For the source codes, you can find them here:
Flash this code to 1st chip, that will act as USB-hid
Flash this code to 2nd chip, that will act as card-reading via SPI
of RFID-RC522 and send the reading via UART to the 1st IC

Here is the new build schematic.

So happy ^.^

Usbasploader that Supports Watchdog Reset, Atmega328p Stuck after Watchdog reset [SOLVED]

Yeah, happy to announced that i have made a little update to
to support the watchdog timer reset. Previously the chip just stuck hung after watchdog is RESET the

So happy ^.^

Usbasploader Hardware Does Not Recognized nor Detected, [SOLVED]

Weird thing happens today, i had written a post how i get my usbasploader board up and running.
And did add some troubleshooting. On my new board the Zener diode 3.3V of D- line is the caused.
I accidently removed got it wrong placed, the arrow pointing to Ground, and my computer had it
detected as Usbasp. But the problem only apply to my new Atmega8A-16PU and Atmega328P-PU.
Works perfect with or without Zener on D- line to my older production year of Atmega8A-16PU and

Atmega8 too.

And also i got so many times failling to have it jump to bootload though the jumper bit is active low.
I just reset the chip rapidly and after 2-3 times of reset it is always detected. Drop me a message
if your board is still not be able be detected. Anyway my usbasploader boards none of them
working on Windows XP, lets forget that OS anyway. :D

Actually replacing the zener 3v6 with Fairchild 55C 3V6
500mW does fix the problem and the device is more stable
as it shown in the schematic.
These are the glass Zener 3v6
500mW Fairchild

Zener diode to replace the ones on
soldered board