Fx2grok

The fx2grok device is intended to be the tinyiest possible Open Hardware FX2 eval board (that can be used as 8-channel logic analyzer).

The schematics and layout are done from scratch in Kicad, and are released under the CC-BY-SA 3.0 license.

Using the open-source fx2lafw firmware (and sigrok, of course) you can use this device as 8-channel logic analyzer.

Goal

• Make the tinyiest-possible Open Hardware Cypress FX2 based 8-channel logic analyzer.
• Optional: Make a tiny 3D-printed enclosure, and/or an "enclosure" using resin (example) with the device (including probes) ideally looking similar to the sigrok logo in the end.

What is NOT the goal?

As you may know, there are tons of FX2-based logic analyzers (and tons of clones) already. There's not much use in creating yet another "standard" device.

The goal of this little hobby project is thus NOT to make a better device, or to make a cheaper device, or anything like that. The only goal is to have it as tiny as possible (it's more of a "just for fun" project).

Status

Work in progress, untested, may or may not work!

First PCB, fx2grok-tiny 0.1, is finished and test boards are ordered. Whether or not everything works as planned is yet to be seen.

Hardware

• 13mm x 13mm PCB
  • 0.8mm PCB thickness, 5mil traces, 6mil trace clearance, 8mil via drill hole diameter, 5mil annular ring.
• Double-sided 2-layer PCB/layout, 0402 SMD components soldered on both sides.
• USB micro-B connector.
• 1.27mm 5x2 pin header.
• FX2 in 56pin QFN package.
• Small SMD 24MHz crystal.
• No buffer or other input protection (not even 100 Ω resistors for each probe).
• No EEPROM, the device will enumerate with the standard Cypress FX2 "unconfigured device" USB VID/PID (04b4:8613).

Download

The schematics, PCB layout and Gerber files are available from the fx2grok git repository:

$ git clone git://sigrok.org/fx2grok

Photos

Schematics, PCB layout, 3D preview

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  Schematics

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  PCB layout

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  3D preview, top

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  3D preview, bottom

Cable

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  Samtec SFSD-05-28-H-10.00-SR

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  Connector with notch

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  Crimp parts

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  Crimp

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  Finished cable

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  Cable with probes

Bill of materials

Note: All prices are for single quantities, most parts get a lot cheaper if you buy higher quantities.

Qty	Device	Footprint	Size	Value	Refdes	Digikey	Mouser	Comments
Required parts
1	Cypress CY7C68013A-56LTXC	QFN-56	8mm x 8mm	—	IC1	10.05€	10.30€	Main chip. Alternatives: Future Electronics: 6.55€ eBay: 4.07€ Aliexpress: 1.52€ (10 pcs lot, 15.16€ total)
1	Amphenol FCI 10118192-0001LF	custom	9.8mm x 5.6mm	—	U1	0.38€	0.35€	USB Micro-B SMD connector
1	Murata XRCGB24M000FAN00R0	custom	2mm x 1.6mm	24MHz	Y1	0.29€	0.46€	24MHz crystal
1	Micrel MIC5504-3.3YM5-TR	SOT-23-5	2.9mm x 1.6mm	3.3V	U2	0.10€	0.10€	3.3V LDO
4	Yageo RC0402JR-072R7L	0402	0.25mm x 0.125mm	2.7 kΩ	R2, R3, R4, R5	0.08€	0.08€	Resistor
1	Samsung RC1005J104CS	0402	0.25mm x 0.125mm	100 kΩ	R1	0.08€	—	Resistor
8	Samsung CL05A104KP5NNNC	0402	0.25mm x 0.125mm	100nF	C2, C5, C7, C8, C10-C13	0.08€	—	Ceramic capacitor
3	Taiyo Yuden JMK105BJ105KV-F	0402	0.25mm x 0.125mm	1uF	C1, C14, C16	0.08€	0.10€	Ceramic capacitor
2	Murata GRM155R61A225KE95D	0402	0.25mm x 0.125mm	2.2uF	C3, C6	0.08€	0.08€	Ceramic capacitor
2	Samsung CL05C120JB5NNNC	0402	0.25mm x 0.125mm	12pF	C4, C9	0.08	—	Ceramic capacitor
1	Vishay VLMB1500-GS08	0402	0.25mm x 0.125mm	—	D1	0.34€	0.51€	LED
Optional parts / variants
1	Amphenol FCI 20021111-00010T4LF	custom	—	—	P1/P2	0.53€	0.55€	5x2 through-hole pin header (1.27mm pitch), could soldered to the PCB (5 pins per side)
1	Amphenol FCI 20021311-00010T4LF	custom	—	—	—	0.68€	0.69€	5x2 connector/receptacle (1.27mm pitch), could be used for soldering the probe cable/wires
1	Samtec TFM-105-01-L-D	custom	—	—	P1/P2	0.53€	—	5x2 through-hole pin header (1.27mm pitch) with a notch, soldered to the PCB (5 pins per side), match for the Samtec SFSD-05-28-H-10.00-SR cable below
1	Samtec SFSD-05-28-H-10.00-SR	custom	—	—	—	4.77€	—	Potential probe cable, needs some crimping

Note: C15 is missing and there is a C16, which is correct. C15 was removed and the numbering wasn't reset.

Resources

• Cypress FX2 overview page
• CY7C68013A, CY7C68014A, CY7C68015A, CY7C68016A datasheet (PDF)
• EZ-USB Technical Reference Manual (TRM) (PDF)
• AN15456 - Guide to a Successful EZ-USB FX2LP Hardware Design (PDF)