We have made an USB dongle based on the nRF24AP2-USB chip. The design is identical to the reference design in the nRF24AP2-USB product description.
It works, but it is not stable. It can run for hours( or less ), then for no apparent reason it stops communicating.
When it stops communicating, the only solution we have found until now is to unplug, then replug the USB dongle.
Stopping and starting the programs does not help. An USB reset ( either via the ANT windows library, or directly via libusb ) does not help. We have been experiencing this behavior with our own software and with ANTware II.
We have tested this on several different PC's, with several versions of Windows ( XP, Vista, 7 ) and several versions of libusb. All combinations has the problem.
We have measured the supply lines on the chip. The VBUS input to the chip depends a bit upon the PC used, but for a 5 V input on the USB plug, the VBUS input on the chip is app. 4.85 V with ~100 mV ripple of ~0.5 ms duration. The VDD pins are at 3.27 V, also with 100 mV ripple, but here with ~100 kHz.
These measurements are made when the chip is sending messages on several shared channels at a rate of app. 100 messages/sec.
Do you have any ideas what can cause these instabilities and/or suggestions what to do to figure out what is going wrong?
Regards,
Klaus Roy-Poulsen
