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Author Topic: FT2232H remains in suspend mode & not able to get detected in Windows/Linux  (Read 330 times)

VVasa

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Hi Team

I am using Ft2232h with my Custom design board. I observed that my pin no.60 (PWREN) is showing 3.3V & pin 36 (Suspend) is showing 0V, I assume that my FTDI is probably in suspend mode and hence not able to get detected on my Windows/Linux system.

I have attached snap from my Schematic. I have observed the following thing:
- Voltage wise its perfect getting 3.3V & 1.8V(VCORE)
- Have checked the assembly wise & its ok
- Also checked by Removing EEPROM
- Many times I have observed Device descriptor failed error message on Windows machine

Questioners:
- Whenever the power ON condition happens does FT2232H needs any particular sequence ?
- What will be the Crystal Frequency to be observed at Oscillator pin's 2 & 3?

Can you please guide through on what can be the solution to remove FT2232H out from Suspend mode ?
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Re: FT2232H remains in suspend mode & not able to get detected in Windows/Linux
« Reply #1 on: September 23, 2021, 12:41:21 PM »

Hi


Power Sequence

It is recommended that VCC, VCCIO and RESET# are set at the same time, I would suggest connecting RESET# and VCCIO to 3V3OUT as this will ensure these are set when VCC is powered.
 
Mixing a bus and self-powered design is not recommended.  VCCIO should be connected to either 5V or 3.3V in one of the following configurations:
 
•   Entirely bus powered, that is from the USB port (VCC and VCCIO pins).  In the case where 3.3V IO's are required a local 3.3V regulator is needed which can be supplied from the USB bus.  Alternatively, in some cases, where only a small amount of current is required (< 5mA), it may be possible to use the in-built regulator of the FTDI device (where available) to supply the 3.3V to VCCIO without any other components being required.  In this case, connect VCCIO to the 3V3OUT pin of the FTDI device.
•   Entirely self-powered, that is from the local supply on your board.  In the case where 3.3V IO's are required, you will need 5V and 3.3V to be available on your board.


Crystal Frequency

Section 6.3 of the FT2232H Datasheet gives an example of a 12MHz crystal being connected in the oscillator configuration.


Suspend State
 
You can read about USB Selective Suspend in AN_107 Advanced Driver Options.

We tell the system we're idle and the system puts us in a low power state.

If it is in selective suspend, the next request through the driver will bring it out of suspend.

For example, in a terminal emulator open port, no data for say 5 seconds will put the device into suspend. The next keystroke will generate a write request. When the driver receives that request, it will come out of suspend and send the data.

There is also an additional feature called remote wake-up which can be used to bring the device out of suspend mode:

RI# pin: Ring Indicator Control Input. When remote wake up is enabled in the internal EEPROM taking RI# low (20ms active low pulse) can be used to resume the PC USB host controller from suspend.

Suspend mode can be monitored via the SLEEP# pin.

please let us know f you have any other questions.

Best Regards

FTDI community
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VVasa

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Re: FT2232H remains in suspend mode & not able to get detected in Windows/Linux
« Reply #2 on: September 24, 2021, 02:29:26 PM »

Thanks for instant reply
FT2232 is entirely self-powered so in schematic if you see VBUS connection on pin 59 is from internally generated 5V regulatory & with same supply we are generating 3.3V, so I think there should not be any issue with Power sequence because all three VCC,VCCIO & RESET are generated at same time.

Also we have a continuous supply of 3.3V on PWRSAV pin 59 & hence I don't think chip is in power down mode. But still FT2232H is not able to enuemerate the USB port. I saw that out 50-60 times I got one time Enuemeration of FTDI chip during that time I measured Clock which was showing 12Mhz & also measured the Suspend pin was showing at Normal Operation. After that I had never got USB enumeration
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Re: FT2232H remains in suspend mode & not able to get detected in Windows/Linux
« Reply #3 on: September 27, 2021, 02:28:25 PM »

Hi

Have you made sure to change the EEPROM settings of the device so that it is in self-powered mode? the datasheet states the following:

" Note that in this set-up, the EEPROM should be configured for self-powered operation and the option
“suspend on DBUS7 low” selected in FT_PROG. Also this configuration uses the pin BCBUS7, so this
assumes that MPSSE mode is not selected."

FT_PROG can be downloaded here

Best regards

FTDI Community
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