Hello,
I am new to electronics but I am hoping to build an interface to connect a computer via USB to a bi-wire serial data stream which is being clocked at 1Mhz. I have considered using a project card such as Arduino but I don't think it runs fast enough to decode my data or act as the interface.

The data in question is Manchester encoded using a clock speed of 1Mhz. I think this means that the data rate is 500 khz. The actual data is MIL STD 1553B for those who are interested; this wraps 16 data bits in 3 sync bits and a parity bit to form what I think is known as a frame of 20 bits.

The initial conversion from Manchester code to NRZ seems simple enough using either a fast comparator or a dedicated encoding/decoding IC (which range from $15-$750). The next stages are the reason for my post:
Q1: What are the methods of converting the NRZ data into either a bit or byte value stream which can be passed to a computer for further processing.
Q2: Once I have my data in a series of bytes (or bits) am I correct in thinking that I could use a FTDI chip (FT2232D USB serial converter) to get the data into the computer?

I can see from reading my own post that I will need some form of clock to define the edges of the pulses.

Thanks for reading and I apologise if I have asked "stupid" questions.

best wishes
Simon

 

What is the source of the 1MHz data? What are you trying to decode?

 

MIL STD 1553b data bus traffic.

 

The applications I have seen that use Manchester Encoding/Decoding used the HD3-6409 IC. Since the Manchester protocol has the clock embedded in the data, the HD3-6409 separates the data and clock and these two signals in turn are fed to a synchronous serial communication port. If all you have access to is an RS-232 port then you could consider building up a synchronous to asynchronous converter using a PIC or an AVR microcontroller. Or you could buy something off the shelf at some place like BlackBox.

hgmjr

 

I have "found" the details about the HD3-6409 chip and think that I might try feeding the output to one of the FTDI USB-serial interface chips.

What type of comms ports are synchronous?

Thanks for your input, I will do a search for "blackbox" to see what they have to offer.

Simon

 

What type of comms ports are synchronous?

Simon

A synchronous serial port has two inputs one input is the serial data stream while the other is the clock for the serial data. The serial clock is most often 16 times the bit-rate of the serial data. Synchronous serial communications ports are not standard on a PC. That is why I suggest you design your own or buy something off the shelf.

hgmjr