hi
I wants to use a smart card for user ID
the code is ready (I re-examined the datasheet and perfectly followed the recommendations), but I do not arrive to communicate with the card!
I wants to use I²C bus, its problem that the exits of the lpc are 3.3v and not 5v??
if some one made already this, or has an idea.
thank you.
just a blind guess, do you have pullups on both SDA and SCL?
Tsvetan
hi
no, i have not pullups on both SDA and SCL
they should be put at 3.3v or 5v?
value of resistance?
thank you
The LPC21XX have 5v tolerant I/O so you can talk to a 5v part with no problems. Since these have to be pulled up you can pull them to what ever the device(s) you need to talk to run at. As for the value of the pull up resistor usally 10k will work fine, if you have alot of devices on the bus you might want to go with a little stronger pullup (lower value resistor).