USB
FREQUENCY COUNTER AND VOLTMETER
Using PIC18F2550 / for connecting analogue
and digital signals to USB port . Included Visual Basic 6 code, Visual Studio 2005 C# code, PIC ASM code, PIC C code and a circuit diagram. The PIC microcontroller
has 10 bit analogue to digital converter, by selecting 8 bits conversion the 2 LSB are ignored. The circuit is powered
by the USB. The interface to the PC is HID class.
The frequency counter has a range of up to 4MHz (24bits). Inputs samplings can be done at rates of 1 per second and 1 every 0.1 second.
HID class (human interface device) is a class of
devices like the mouse and the keyboard, the data transfer rate
is limited to 64KB/S. The PC already has a driver for HID USB.
C# code is modified Microchip code from the USB framework, Microchip Solutions v2012-04-03.
VB6 code includes guidance to setting up the PC.
The PC register the PID and VID (product ID) of the USB device when
it's plugged, the VB code uses these ID's to communicate with the
device. For commercial VID it is needed to buy it from USB-IF, but in your lab you can use any number.
PIC16F1459
The PIC16F1459 is a cheap option
for pic18f2550. Included Visual Basic 6 code, Visual Studio 2005 C# code, PIC C code
for MPLABX and a circuit diagram.
The source code is derived from freeware from these sources: http://janaxelson.com/usb.htm , http://openprog.altervista.org/USB_firm_eng.html
You are free to use the circuit diagram and the VB software with no
limitations.
USB FREQUENCY COUNTER AND VOLTMETER FOR
ANDROID
Using PIC18F2550 for connecting analogue
and digital signals to Android USB port . The Android USB port is
easily accessed by imitating keyboard. PIC C code is Microchip sample
code for USB Keyboard. The file Keyboard.c has the added code for the ADC
and the frequency counter from line 900. The USB sends 1 bytes at a
time for each key, the 11 digits of the counter and voltage are sent in 30
bytes. The HEX file is included, the c code can be compiled using C18
v3.43 with MPLAB. The Android app is in BASIC! graphic text.
http://mougino.free.fr/rfo-basic/index.html . The app uses
graphic screen to displays voltage and frequency. The .apk file is the
file that installs manually the app to your phone. For editing the app the .bas file can be
imported after you install the RFO BASIC app to your PC and or your Android device.
HID class (human interface device) is a class of
devices like the mouse and the keyboard, the data transfer rate
is limited to 64KB/S. The PC already has a driver for HID USB.

The Android App

The VB6 application is a combined digital and analogue
voltmeter.
Circuit Description
See also Technical Tips
Analogue input, voltage range 0 to 5V. Max input voltage
is 5.5V .
The counter input, TTL voltage levels.
3.3V internal supply for the USB transceiver. 0.22uF is
required for regulation.
D+ D- are the data lines to the USB connector on the PC.
For USB wiring info: http://www.interfacebus.com/Design_Connector_USB.html |