- on Microcontrollers
- Published in issue 11/2002 on page 0
USB Driver Programming (2)
writing your own device driver
In the previous issue of Elektor Electronics, we described how device drivers are used. Now it’s time to modify a Cypress device driver. You only need a couple of programs for this, even if you have never worked with Microsoft Visual Studios. All of the necessary steps are described in minute detail.In the Windows Device Manager, you will see all currently connected USB devices listed under ‘USB Controller’. Figure 1 shows the entries for a USB device using the Cypress IC with no EEPROM and a USB data spy for Bin-Term.Writing your own complete driver ‘from the ground up’ is almost impossible for normal mortals. Fortunately, Cypress provides the EZUSB driver not only as an installable version, but also in the form of source code.
In some cases, the chip will not respond and all ports will remain low. Although Windows has detected that a new USB device has been connected, this will be not recognized. The problem is solved by fitting pull-up resistors R3 and R2 as indicated in Figure 1. These resistors should not be omitted.