|
|
Light Control
| Re: MCP23x17 question |
Author: Phil Short
Date: 01-31-10 12:07
A couple of more comments...
Per the spec, the CS/ pin on the 23S17 part is active low.
Also, the data pins on a lot of parallel ports may only go up to 3V (or so), not all the way to 5V. This will cause problems with chips that need an input voltage of >4V (like the part that you're using). The control pins (such as pin 1) are open collector (or open drain), and will go all the way up to +5 (although you need to check this, since some controllers may omit the pullup resistor, expecting it to be on the external device). The bottom line is that you need to measure the output voltages from your parallel port to make sure that they go high enough for the 23S17 part (since it is not guaranteed by the parallel port specs). If there is a problem here, you might try changing the parallel port mode in the PC BIOS and see if the problem is fixed in one of the other modes.
|
|
| Topics |
Author |
Date |
|
D McLeod |
01-23-10 09:26 |
|
Phil Short |
01-30-10 13:46 |
|
Frank van der Hulst |
01-30-10 17:12 |
   |
Re: MCP23x17 question new |
|
Phil Short |
01-31-10 12:07 |
NOTE: You are not currently logged in. If you wish to post any messages to this board, you must be logged in.
You may register here
or login here.
|
|
|
