Search found 5 matches

by brandts
17 May 2011, 13:08
Forum: Mindstorms Hardware
Topic: Need help with PCF8574
Replies: 11
Views: 8584

Re: Need help with PCF8574

> philoo That's not a stupid question because I think more people make this mistake. In the attachment I numbered the pins how I think they should be. > h-g-t As mentioned above I tried both address but they both don't work. After that I did connect the chip to a motor port to see if any of the led ...
by brandts
16 May 2011, 12:53
Forum: Mindstorms Hardware
Topic: Need help with PCF8574
Replies: 11
Views: 8584

Re: Need help with PCF8574

In not sure that the IC is fried. Is it possible that I damaged something inside the chip with soldering the contacts? Is there a way to measure this with a multimeter?

I have the second edition of Extreme NXT so that indeed explains why the sample code is different.
by brandts
16 May 2011, 12:35
Forum: Mindstorms Hardware
Topic: Need help with PCF8574
Replies: 11
Views: 8584

Re: Need help with PCF8574

The book I used is "Extreme NXT: Extending the LEGO MINDSTORMS NXT to the Next Level". The program I used looks like this: #define I2Cport S1 // Port number #define I2CAddr8574 0x70 // I2C address x040 8574 or 0x70 for 8574A byte WriteBuf[]={I2CAddr8574,0x00}; // write buffer is addr and data task m...
by brandts
16 May 2011, 12:01
Forum: Mindstorms Hardware
Topic: Need help with PCF8574
Replies: 11
Views: 8584

Re: Need help with PCF8574

I use discrete parts. I bought a PCF8574AP fabricated by NXP: http://www.nxp.com/documents/data_sheet/PCF8574.pdf and got some leds, wires and resistors from my work. I soldered it all together on a standard solder board (similar like: http://itp.nyu.edu/physcomp/Tutorials/SolderingAPerfBoard). I ha...
by brandts
16 May 2011, 10:30
Forum: Mindstorms Hardware
Topic: Need help with PCF8574
Replies: 11
Views: 8584

Need help with PCF8574

Hi everyone, I'm trying to control 8 leds using a PCF8574 according to the scheme as seen in the attachment (from the book NXT Extreme). The problem is that I can't control the leds. If I connect the PCF to the NXT only 4 leds are turned on continously (the leds connected to P0, P1, P2 and P3) and t...