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 on: January 18, 2021, 02:22:09 PM 
Started by johnlon - Last Post by johnlon
I believe the UM245R has 200k pull ups on the D0-D7 data pins - is this correct?

When neither the read nor write control lines are enabled then I expect the data lines to go into a high impedance state with this weak 200k pull up  - is this all correct?

The bus that I am connecting the UM245R to already has a weak pull down, therefore I want to avoid a situation where the UM245R is pulling up and the surrounding circuit is pulling down - it's an irritating tug of war at the very least, but there is some more irritating impact in my circuit (see the post script).

Is there a means to either disaable the pull up entirely OR change the UM245R so that it pulls down instead of pulling up.

What are my options?


PS. The impact of the 200k pull up in the UM245R is that an LED array that is directly attached to the bus lights up when nothing is asserting on the bus.
200K is enough on 5v to allow 15 to 20uAmp to flow and these LED's are really efficient and glow nicely at that current. I would rather thay were dark.
Of course I can use a 10k pull down to overcome the UM245R pull ups but that's a bit irritating.

 on: January 18, 2021, 02:09:08 PM 
Started by johnlon - Last Post by johnlon
The UM245R documentation says that if I want self powered mode then I need to make a few specific wiring changes over the default USB powered.
In addition the doco says I also need to use the FT_Prog utility to change the EPROM from 'Bus Powered' to 'Self Powered'.

On the FT_Prog page where I change the power setting to "self powered" there is also a setting for the current that may be drawn from the bus.
It has a default of 100ma for the current draw from USB.

Does this actually limit the current draw by the device in some way - if so is there further doco and examples of how this is useful.

The documentaiton mentions "hybrid" power but doesn't give any indivation of how or where this mighty be useful.

Any further references?

 on: January 18, 2021, 02:06:56 PM 
Started by johnlon - Last Post by johnlon
The UM245R documentation says that if I want self powered mode then I need to make a few specific wiring changes over the default USB powered.
In addition the doco says I also need to use the FT_Prog utility to change the EPROM from 'Bus Powered' to 'Self Powered'.

I would like to understand what is the actual impact in the internal behaviour of the device when making this change?

If I make the wiring changes but forget to make the EPROM change to "Self powered" then will the device fail to work properly if I put it on self power?
And if so then what is it that actually causes the failure?


Can someone confirm that this eprom setting is purely informational to the host. If I leave it set to "Bus powered" but in fact run in self powered mode then what are the negative consequences if any. Are there in fact zero negative consequences???

 on: January 18, 2021, 02:00:58 PM 
Started by johnlon - Last Post by johnlon
Hi where can I find documentation on defaults such as BUAD rate for this device.
By experimentation I was able to discover that the device worked ok at 115k but at 9600 which was the default for my serial terminal I got the usual '?' character instead.
I am using the VCP (com port) approach to talk to it.

Curiously I was able to transmit a single character at a time from the PC to the device over USB/VCP when using 9600, but was unable to communicate back to the PC from the UM245R without setting the serial terminal to 115k. I'm not clear why this might be.

But, more importantly where is the documentaiton covering such things as the speed / marity etc etc that need to be set.

Also is it possible to configure the UM245R to use different setting if needed (out of curiosity).

 on: January 18, 2021, 11:32:41 AM 
Started by LennonNM - Last Post by FTDI Community

Although the FT4222H uses a data byte of 8 bits, most SPI peripherals can still use this so long as you keep CS asserted as they still see this as one transfer.

It looks like this particular device has some kind of timeout if the clock sits low for more than 28ms but beyond that was there any other reason why it could not accept multiple bytes so long as CS is kept asserted?

MPSSE (for example the FT232H) would have been another option but can only do SPI modes 0 and 2 and it looks like this ADC may need mode 1.

Best Regards, FTDI Community

 on: January 15, 2021, 04:30:43 PM 
Started by Anshumantech - Last Post by FTDI Community

Unfortunately we don't have any experience with impact or Quartus (Altera) package.
These packages require specific hardware to program FPGAs as mentioned in an external forum that you have created:


If no-one else on this FTDI community website can help, it may be worthwhile contacting Altera.
Another community user already replied to one of your posts on this:


If you are trying to clone FPGA programmers that’s not something we can support.

The FT232H uses our standard VCP Drivers or D2XX Drivers.

Best Regards,
FTDI Community

 on: January 15, 2021, 02:15:34 PM 
Started by LennonNM - Last Post by LennonNM
Hi, I'm trying to make an interface in python, first of all, if someone knows of a package (other than python-ft4222) or an alternative library to Libft4222 from FTDI (they already answered me that this library does not have the functionality I require), please tell me.

For the frame data, I require to communicate with a ADS1118 temperature sensor, which requires minimum 16 bit data frame, as told by FTDI reps, Libft4222 (therefore, also python-ft4222) only operates at 8 bit data frame, so I'm getting a "gap" in between each byte. Does someone know a workaround to get at least 16 continuous bits?

Thanks in advance.

 on: January 14, 2021, 05:35:32 AM 
Started by Anshumantech - Last Post by Anshumantech

a) We made a general purpose module of FT232H. For various applications of USB to JTAG, SPI, I2C etc.
b) We could easily program Spartan 3 or Spartan 6 Xilinx FPGA using "xc3sprog" freeware s/w.
c) Now we want to use this module under impact or Quartus (Altera) package to program other 5V devices like CPLD or 50AN or Cyclone 2 or Cyclone 4 etc.
Can you guide about needed driver s/w needed to achieve the above one or all?

Thank you in advance.

 on: January 13, 2021, 04:33:19 PM 
Started by Marcoz - Last Post by FTDI Community

The LibFT4222 API return code 1000 is FT4222_DEVICE_NOT_SUPPORTED.

Which revision of silicon are you using?

Which mode are you using the device in? Which hardware are you using?

Which version of the D2xx driver are you using and which version of LibFT4222?
Note the following versions for the 64bit dlls and libs:

.\CDM v2.12.28 WHQL Certified\amd64

This issue has never been reported before.
Have you tried the 32bit and 64bit dlls with the standard examples provided with LibFT4222? This would take the python aspect out of the equation, if you say that it’s a problem with our dll:


Unfortunately we have no support for Python, but you can check out the following information with respect to the D2xx driver (not specifically LibFT4222):

It is possible implement the D2XX driver in python scripts.

The following imports are required:

import os
import sys
import ctypes

And the library can be loaded in the following manner:

class D2XXTest(object):
    def __init__(self):
        #Load driver binaries
        if sys.platform.startswith('linux'):
            self.d2xx = ctypes.cdll.LoadLibrary("libftd2xx.so")
        elif sys.platform.startswith('darwin'):
            self.d2xx = ctypes.cdll.LoadLibrary("libftd2xx.1.1.0.dylib")
            self.d2xx = ctypes.windll.LoadLibrary("ftd2xx")
        print 'D2XX library loaded OK'

Also see some other Third Party Implementations:

ctypes Wrapper for D2XX:

I found one for LibFT4222 also:

There also may be other FTDI Community users with Python knowledge and LibFT4222 who may be able to help you further.

Best Regards,
FTDI Community

 on: January 13, 2021, 07:41:30 AM 
Started by ol_devel - Last Post by ol_devel
Thank you for your reply.

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