From: BRACH v. <v....@fr...> - 2006-02-11 09:32:06
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Yes Royce you're right, Input current in low level output is not enough to drive led I confuse with TTL standard output. For P1 drection I remember an 8x51 base controler I used must first write for indicate direction but maybe not on at89c52 Vinzzz > Hi, > On Fri, 03 Feb 2006 16:43:23 +0530, BRACH Vincent <v....@sm...> wrote: > > > On 51 base microcontroler on P1 and P3 port used as IO, you must write > > (before writing your output value) one time on P1 or P3 to specifie the > > direction of the IOs : > > > > void main(void) > > { > > P1 = 0x00 ; // all pin of P1 port are standard IO in output mode > > P1 = 0x0F ; // Led On on b7 to b4 on P1 > > while (1) ; > > } > > This is not needed at all. Nyugen's code is correct as far as P1 is concerned. > > > > > (for current specification you MUST turn on LEDs on low level, high > > level have'nt enough ouput current to turn on a LED) > > > > ____ > > | > > | Vcc > > | | > > | _|_ > > | _\_/_ LED > > | | > > 8 | | > > 9 | | | R > > c | |_| > > 5 |P1.4 | > > 2 |------- LED turn on with low level on P1.4 > > ____| > > > > In AT89c52, the current capacity even in sink mode is not enough to light an LED (AT89c2051 has 20ma sink capacity). It may damage the pin. Use a buffer or transistor switch. > > Nyugen, have you tried manually lighting up your LEDs by removing the 89c52 shorting the relevent pins to ground? Maybe a hardware problem? > > An aside: -o myfile.hex option on SDCC command line gives you your *.hex suffix. I have never had to use packihx. > > --Royce. > > ---------------- > Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ > -- > Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ > > > ------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. Do you grep through log files > for problems? Stop! Download the new AJAX search engine that makes > searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 > _______________________________________________ > Sdcc-user mailing list > Sdc...@li... > https://lists.sourceforge.net/lists/listinfo/sdcc-user > |