Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

impedance matching for MCU communications? needed?

Status
Not open for further replies.

fala

Full Member level 5
Joined
Sep 18, 2005
Messages
249
Helped
19
Reputation
38
Reaction score
4
Trophy points
1,298
Activity points
3,569
Hello board, I read in an article by "Keith Armstrong" that for fast TTL
(rise time 2ns or less) I should consider impedance matching for nets longer than 15Cm. I have an AVR(ATMega128) master MCU @16MHz that it's SPI runs at about 1Mbit/Sec. I want to connect it to 8 slave MCUs which are placed in other PCBs, total distance will be in the range of 40-60Cm for each Slave MCU. In datasheet of my AVR fall /risetime of SPI interface has been assigned
"TBD" which I'm not quit sure what it means(maybe To Be Determined....). anyway if we consider it as fast logic do I need impedance matching? for reliable communication? Dose placing just a resistor at source can alleviate the problems? do I need impedance match for tracks?

Thanks,
 

tycheng

Junior Member level 3
Joined
Apr 17, 2007
Messages
31
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,286
Activity points
1,425
I think you need to match your 8 slave MCUs
with simple resistors. but you need to check the driving capability of master MCU.

ty
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top