[Coco] USB (RS-232?) O-scope

[Frank Swygert]

Saw this at 
http://www.instructables.com/id/DPScope-Build-Your-Own-USBPC-Based-Oscilloscope/ 
and thought some of you might be interested. Looks like a good way to 
get a cheap o-scope, but I'm not sure if the specs are good enough for 
working with a CoCo. The only drawback is the software is Windows based, 
but maybe one of you Linux guys can fix that -- or it might run under 
WINE, or could be run in a virtual PC window....  It uses a USB 
interface, but it should be convertible to RS-232. Uses a PIC 
microcontroller. If RS-232 is doable I wonder if software could be 
written for a CoCo? Since the PIC is doing most of  the work the 
computer should just be a display device, but the CoCo screen or serial 
might not be capable of displaying fast enough -- then someone has to 
write the software too...

*Input:
*      
Number of channels: 2
Analog bandwidth: > 1.3 MHz
Input impedance: 1 MOhm || 15 pF
Probe connection: BNC
Usable probe types: Standard 1:1, 1:10, 1:20 probes

*Vertical (voltage) scale:
*
Vertical sensitivity (20 divisions):
- 5 mV/div to 1 V/div (1:1 probe)
- 50 mV/div to 10 V/div (1:10 probe)
- 100 mV/div to 20 V/div (1:20 probe)

Vertical offset: 0 - 20 divisions

Maximum voltage range   
-12V ... 20V (1:1 probe)
-120V ... +200V (1:10 probe)
-240V ... +400V (1:20 probe)

Probe compensation: yes (2 kHz calibration output)

Offset adjustment: yes

*Horizontal (time) scale:
*      
Max. sample rate (single shot): 1 MSample/sec
Max. sample rate (repetitive signals): 20 MSamples/sec

Timebase settings (scope mode): 0.5 usec/div ... 1 sec/div
Timebase settings (datalogger/roll mode): 0.5 sec/div ... 1 hr/div

*Trigger:
*
Trigger source: CH1, CH2, auto (free run)
Trigger polarity: rising edge, falling edge
Trigger noise reject: yes (selectable)
Pre-trigger capability (i.e. can show what happened
before the trigger event): 0 - 20 divisions
Post-trigger delay (delayed scan, to look at the
signal long after the trigger event but with high
resolution): 0 - 200 divisions

*Acquisition:
*
Record length (normal mode): 200 points/channel
Record length (FFT mode): 400 points/channel
Max. screen refresh rate: up to 40+ frames/sec
Datalogger mode (roll mode): yes (data can be logged to file in real time)

*Display:* *
*
Real-time FFT: yes
FFT filters: Rectangular, Hanning, Hamming, Blackman
Averaging: yes (2 / 5 / 10 / 20 / 50 / 100)
X-Y mode: yes
Display styles (can be combined): Points, Vectors (Lines), Infinite 
Persistence

Time and level measurements: yes (using cursors)

*Save & Restore:
*
Waveform export (e.g. to Excel):yes (CSV format)

Save/restore of scope setups: yes

*PC Software:
*      
PC connection: USB, 500 kbaud
PC software: Windows 2000, XP (SP3), Vista, 7
Minimum screen size: 800 x 600 pixel

*Mechanical construction:
*
Power supply: through USB (5V / 250mA)
(external supply 7.5 - 9V / 300mA optional)

-- 
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)