Hi,

I have made a schematic for FT232HL based USB-SPI programmer to flash my ice40 lattice FPGA board. I have attached the schematic below, no matter what I did the chip is not getting enumerated at all. I am not sure what's happening. Initially i forgot to add 12k ohms REF pin resistor but got it added later externally but still nothing is happening. I have intentionally skipped adding the EEPROM chip as some schematics didn't have it. Is it absolutely mandatory?

 

If the voltages are ok, I suggest you to add capacitors to each power pin. And also didn't really understand the idea to connect EEDATA (pin 43) directly to 3.3V

 

Hi,

I have made a schematic for FT232HL based USB-SPI programmer to flash my ice40 lattice FPGA board. I have attached the schematic below, no matter what I did the chip is not getting enumerated at all. I am not sure what's happening. Initially i forgot to add 12k ohms REF pin resistor but got it added later externally but still nothing is happening. I have intentionally skipped adding the EEPROM chip as some schematics didn't have it. Is it absolutely mandatory?

View attachment 362895

why is ref to 2k2 , where as demo its 12k?

should reset have a delay , rc network ?

is your wirring good, the dp and dn need to be a transmission line , matched length, no / matched number of vias etc.

vpll et all need better / recomended decoupling .
there are good referance designs and layouts on the web site , copy them.

I dont know on usbc, check those cc1 , 2 resistors.

 

why is ref to 2k2 , where as demo its 12k?

That was a schematic mistake sorry, in the real board 12k is soldered.

there are good referance designs and layouts on the web site , copy them.

I actually did the same but still couldn't get it working.

I dont know on usbc, check those cc1 , 2 resistors.

USB-C requires CC1 and CC2 to be tied to ground through a 5.1k resistors to enable 5V Power delivery so that connection is correct.

 

Hi,

I have made a schematic for FT232HL based USB-SPI programmer to flash my ice40 lattice FPGA board. I have attached the schematic below, no matter what I did the chip is not getting enumerated at all. I am not sure what's happening. Initially i forgot to add 12k ohms REF pin resistor but got it added later externally but still nothing is happening. I have intentionally skipped adding the EEPROM chip as some schematics didn't have it. Is it absolutely mandatory?

View attachment 362895

Why not just use this?

https://learn.adafruit.com/adafruit-ft232h-breakout

I used one to develop a .Net app on a PC, that controls this using SPI

https://www.amazon.com/dp/B0CDH1JJZG?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1

Very robust setup.

 

one problem is that it is not powered - pin 39 need to be connected to 3V3.
also not sure it will work with external oscillator. that works in some cases but some products require settings to permit this. don't know in which category FT232 falls.
also not sure it will work without Eprom... that is where settings are stored. without this it may work but will always fall back to factory defaults.
https://learn.adafruit.com/assets/88382

 

Why not just use this?

Yes I learnt this lately, finally purchasing this module. FT2232H-56Q Mini Module
Will update more thanks

 

pin 39 need to be connected to 3V3.

I have bridged it with external soldering even after that it didn't work.

also not sure it will work with external oscillator

FTDI datasheet suggests it's possible and chip should work out of the box.

also not sure it will work without Eprom... that is where settings are stored

Yes that's my worry too, I am now unsure how to program this EEPROM also? I saw there are tools like FTProg but even without EEPROM the device should atleast enumerate as something, in my case it's doing nothing.

 

I have bridged it with external soldering even after that it didn't work.


FTDI datasheet suggests it's possible and chip should work out of the box.


Yes that's my worry too, I am now unsure how to program this EEPROM also? I saw there are tools like FTProg but even without EEPROM the device should atleast enumerate as something, in my case it's doing nothing.

The ftdi does not need an eeprom to use default values .
...
Vcc is interesting , it's all over the circuit but as mentioned seems to have no source .

You have not as far as I remember expanded on how you have routed the dp and dn lines .can you share photo please .

 

You have not as far as I remember expanded on how you have routed the dp and dn lines .can you share photo please .

Sure here it is, it's a 2 layer board but not length matched but I've seen connections like these work in many boards as the distance between connector & chip is very close.

 

when i am in a hurry and just want things to work, i stick with defaults and at least leave room to implement other features or options - in case it comes to that later on. as mentioned before, i have not used that chip but did check datasheet (skim mode) and chatted with Google AI. so there are couple of traps:

power... Vregin is meant to connect to USB 5V rail (VBUS). but if it is connected to 3V3 then pin 39 must be connected to it. (fixed). and this too must be clean and stable.

core voltage... it must measure exactly 1.8V. also the 0.1uF capacitor here is a major problem. it need to be 3.3 - 4.7uF. if this is not rock stable, serial interface engine will not even initialize. the 0.1uF is the minimum value (and it is listed in datasheet) but some other documents like official reference design often use 0.1uF in parallel with 4.7uF (needed for high speed - which chip defaults to when no EEPROM)

oscillator... are you sure that chosen component is a 3V3 part and not 5V? are you sure it works? do you have an oscilloscope? is this precision part? according to AI if this is not 12.000MHz +/-0.05% the unit will fail to sync with PC.

EEPROM... is just the EEPROM missing or also the pullup resistors are not populated? if they are missing chip may be pickup noise and think that EEPROM is there but corrupt which stall startup.

good luck...

 

Sure here it is, it's a 2 layer board but not length matched but I've seen connections like these work in many boards as the distance between connector & chip is very close.
View attachment 362956

not length matched
not transmision lines
massive loop
what are those vias ?
whats the ground plane like ?
have you looked at any usb3 referance layouts ?

it might work, but !!

 

Yes I learnt this lately, finally purchasing this module. FT2232H-56Q Mini Module
Will update more thanks

It's a sophisticated device, it requires a device driver, but the software works very well. Just add the relevant nuget package and its pretty straightforward, let me know if you think I can help with any details, source code etc.