Lcsoft Mini Board

Lcsoft CY7C68013A Mini Board

Back of PCB

This is a barebones development board for the Cypress FX2 chip, as used in the Saleae Logic and other boards. It is available on Ebay for less than €15, or Taobao for even less.

Hardware

All the pins on the FX2 are broken out to 40 header pins. There's an on/off toggle switch, a reset button, and a jumper that lets you select whether the FX2 gets its configuration from a small EEPROM, or boots into the default mode. The EEPROM's default settings make it come up with the same VID:PID as a Saleae board.

Driver

The board is fully supported by sigrok, using the fx2lafw driver.

Possible Issues

• With some kernel versions, and if the onboard eeprom is disconnected (the jumper not connected) the kernel will automatically claim the device with a "usbtest" kernel module, seen in dmesg like "usbtest 2-2:1.0: FX2 device" --- if this happens, sigrok will be unable to claim the device, remove the "usbtest" kernel module as root to be able to use it:

$ sudo rmmod usbtest

You can add the usbtest permanently to a module blacklist, at least in debian-based distributions found in /etc/modprobe.d/blacklist.conf :

$ sudo sh -c "echo 'blacklist usbtest' >> /etc/modprobe.d/blacklist.conf"

Required Testing Hardware Extensions

Do not directly hook the board pins to another circuit, if you don't know what you are doing! This could damage the board!

The simplest circuit would be adding at least resistors in between your circuit-in-test and the LCSoft board, but be aware here that this cypress chip can only tolerate a maximum of 5V I/O. Better would be to use a clamp circuit like shown at Spiralbrain's Blog (but you do not need to add another eeprom for sigrok with fx2lafw!). A buffer circuit using a 74HC241 IC for protection is also possible. Check on the fx2lafw page to see which protection circuits are used on other logic analyzer boards.