1
\$\begingroup\$

I am doing my own development board using LPC1343.I gone through the application note AN10986.I noticed the topic "Automating USB ISP".In that they described about USB softconnect. Now I am designing the board,a question arises whether is it necessary to use that softconnect or manual working is enough?....and also how much voltage(minimum) should be supplied to the VUSB pin to detect as USB ISP.

\$\endgroup\$
  • \$\begingroup\$ You are asking if its okay to just use the manual USB ISP method and disregard the softconnect? Or am I missing something? \$\endgroup\$ – Funkyguy Sep 22 '15 at 21:27
  • \$\begingroup\$ absolutely what you meant is right.... \$\endgroup\$ – Aadarsh Sep 24 '15 at 17:19
1
\$\begingroup\$

You don't need to use the softconnect if you don't want to. The manual method will work perfectly fine.

The VBUS pin is usually set at 5V as that is the standard voltage for the USB power lines. The controller will be looking for that voltage.

\$\endgroup\$
  • \$\begingroup\$ Is that 5V will burn my chip?.How much is the maximum voltage to be supplied to Vdd(IO)?.How much voltage will the chip will work fine without burning or malfunctioning.Is it necessary to control current passing through the Vdd and Vio?Is it safe to give the full 5V to the VUSB from the PC to the chip directly.I am using a 2Kohm resistor along with 100Kohm pull down resistor to ground.Is it okay? \$\endgroup\$ – Aadarsh Sep 24 '15 at 17:27
  • \$\begingroup\$ Itll be fine but if you have doubts, look at the data sheet for your chip. It'll have absolute maximum ratings for all input voltages, including VBUS. It's a standardized voltage from the USB specification \$\endgroup\$ – Funkyguy Sep 24 '15 at 17:30
  • \$\begingroup\$ Why are you using the resistors? Where did you get information that led you to believe you need those? \$\endgroup\$ – Funkyguy Sep 24 '15 at 17:31
  • \$\begingroup\$ I saw the schematics of this website see this.In that board they used lots of resistors and a transistor.I took that board as my reference.I am much feared that whether my chip will burn or malfunction,if I dont take precaution on voltage range and designing. \$\endgroup\$ – Aadarsh Sep 25 '15 at 17:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.