• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Low-clocked microcontroller with a high-speed interface??

Not open for further replies.


New Member
My problem is as follows....

I'm currently theorizing the implementation of a video capture device using Texas Instruments' TVP5145 video encoder(http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=TVP5145) and Philips' ISP1581 USB interface device(http://www.semiconductors.philips.com/pip/ISP1581BD.html, compliant with USB 2.0 standards and data rates up to 480Mb/sec).

The idea is to send digitized video from the TVP5145 to the ISP1581 via the microcontroller interface or the DMA block.

Now, how exactly do data rates get up to 480Mb/sec if I were to say... use a 8051 microcontroller with a 24MHz clock?

The specs on the ISP1581 say the MCU must setup the internal TX FIFOs so a packet is sent through USB interface. Thinking with Atmel AT89(8051) series MCU in mind, 1 machine cycle requires 12 oscillator periods, so that means at 24MHz there is only 2 MIPS (correct me if I'm wrong). Say there needs to be about 7 instructions to fully execute a packet transmit, does this mean I can execute a packet transmit 285,714 times in 1 second??
(2 million instructions per second / 7 ~= 285,714.286)

so say a packet contains 1 byte of data of useful data, that is only about 285Kb/sec.

I would obviously have to send digitized video(which is sampled at about 30MHz) from the TVP5145 to the ISP1581 fast enough so that information isn't lost. Is this possible with a microcontroller that is clock at a SLOWER speed than 30MHz? Buffers perahps??

ANY help/ideas/corrections would be nice, thanks.


Active Member
You probably need a 6-clock instruction cycle derivatives of 8051. There are many available. Search for them. Or you might need even faster RISC 1-clock instruction cycle CPUs like PIC. You can also try Cygnal's C8051Fxxx family. They say it has max. throughput of 25 MIPS - even faster than PICs.
Not open for further replies.

Latest threads

EE World Online Articles