FTDI Community

General Category => Discussion - Hardware => Topic started by: pejvaak on November 27, 2017, 09:36:04 AM

Title: SPI mode clock duty cycle
Post by: pejvaak on November 27, 2017, 09:36:04 AM

Hi

We face a rather strange status on the circuit using FT2232H. We need to use the SPI at 3 MBit/s. By probing the lines with scope, it turn out that the duty cycle of the clock is around 25% and in fact we are not getting the speed that we needed.

Any suggestion?

Title: Re: SPI mode clock duty cycle
Post by: FTDI Community on November 27, 2017, 04:55:04 PM

Have a look at AN_114 - Interfacing FT2232H Hi-Speed Devices To SPI Bus (http://www.ftdichip.com/Support/Documents/AppNotes/AN_114_FTDI_Hi_Speed_USB_To_SPI_Example.pdf). It provides details on how to interface and configure the FT2232H to read and write data from a host PC to a serial EEPROM over the serial SPI interface bus. It illustrates, via an example, how to use the MPSSE of the FT2232H to interface with the SPI bus and also shows examples of the read and write waveforms on the SPI interface.

Thanks,
FTDI Community

Title: Re: SPI mode clock duty cycle
Post by: cioma on January 09, 2018, 11:54:34 AM

Do you by any chance have 3-phase clocking enabled?