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.

Review - Hardware Design

Status
Not open for further replies.

davidlee11

Newbie level 2
Joined
Jun 24, 2015
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
14
Switch Schematic.png

As a newbie, Switch section is designed according to my knowledge. Please let me know the review for this section.

Switch is connected with the microcontroller. I have tried to protect microcontroller from positive & negative spike. The distance of switch from microcontroller is approx. 6 Inches. Here Vcc is 3.3V & microcontroller also works on 3.3V.
The schematic for the switch section is attached.
 

D.A.(Tony)Stewart

Advanced Member level 5
Joined
Sep 26, 2007
Messages
7,078
Helped
1,724
Reputation
3,447
Reaction score
1,729
Trophy points
1,413
Location
Richmond Hill, ON, Canada
Activity points
51,937
A similar R/CR diode structure is built into every input. See ESD protection current. Ensure switch is isolated from finger discharges to signals with 15 mm clearance for 15kV isolation. Do you want cap at 0V on power up then pulled up with switch to ground and power up closure? DOes it have software controlled pullup on input?

Choose RC >> debounce time for switch depending on size /quality 1~10ms typ.switches.
 

davidlee11

Newbie level 2
Joined
Jun 24, 2015
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
14
The microcontroller will measure 0V when switch is pressed. It has software controlled pull up resistor.
 

KlausST

Super Moderator
Staff member
Joined
Apr 17, 2014
Messages
22,499
Helped
4,643
Reputation
9,302
Reaction score
4,946
Trophy points
1,393
Activity points
148,649
Hi,

the switch ON time constant is about 110us (falling)
the switch OFF time constant is about 22ms (rising)

These values are OK even for debouncing.

The protection seems to be OK as well.

if a high energy positive pulse comes in, then it may lift the VCC voltage. Use an adequate bulk capacitor at vcc.

Klaus
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top