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USB Low-Full-High Speed Peripherals

New Contributor

Hello,

I'm new in the world of cypress mcu's. Having that in mind, I will ask two probably funny questions. Here is my current state: I have a device with CY7C68013A 100pin version(the mcu hereafter) and a 4k eeprom chip onboard. Eeprom is programmed for C2 load  (both VID/PID and program load), but the mcu is dead-literally. I've managed to replace the mcu with 128 pin version (don't ask how).

The problem is this:

after connecting the board (with eeprom disconnected from the mcu) to USB port on a PC, there is a delay of 15 sec. after which PC throws: Unknown USB device(device descriptor request failed) and device HID property is:USB\VID_0000&PID_0002\5&1C38AEC2&0&8 . I know this is the enumeration process failure, which means the mcu didn't enumerate with hardwired VID/PID.

My question 1 is this:

since 128 pin version has EA pin which should be pulled down/up to enable/disable loading of a program from an off-chip RAM, could letting it float be the reason for this behavior? 

My question 2 is this:

Is there any other quirk I should address to make it work?

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Moderator
Moderator

Hello,

The EA pin should be pulled low when 8051 is loading the program from internal FX2LP RAM.

Since you are not using a C2 load or a C0 load, the FX2LP will enumerate with VID,PID and DID provided by the hardwired internal logic.

The 128 pin package has the same functionality as that of 100 pin. So this should not be a issue.

Best Regards,

Yatheesh

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Moderator
Moderator

Hello,

The EA pin should be pulled low when 8051 is loading the program from internal FX2LP RAM.

Since you are not using a C2 load or a C0 load, the FX2LP will enumerate with VID,PID and DID provided by the hardwired internal logic.

The 128 pin package has the same functionality as that of 100 pin. So this should not be a issue.

Best Regards,

Yatheesh

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New Contributor

Thanks for your answer, but I guess my question really is :

do I HAVE TO pull down/up the EA pin in order to get mcu work? From the logic point of view, the state of this pin is irrelevant for the mcu to enumerate  it self as the default device...

Edit:

It turned out  it HAS to be ether pulled down or up, floating is unacceptable. I've made a mistake and broken the EA pin on the chip, and that's way I was hoping I won't have to order another one and wait for shipping...anyway, with some precise soldering I've got it done. So, ,thanks for your help.

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