Hi,everyone Are you using a keyboard management IC? Which one is the best? Take 4 X 4 keyboard for a example! Discuss it!
hi, If you let the MCU scan keyboards,it will also take much CPU time Here it is implemented via 1/50s interrupt and takes about 30 assembly commands with total time about 20mks - 0.1% of processor time (= good days!
Somehow, you seem to have escaped Graham Cole's war on off-topic posts: http://www.keil.com/forum/docs/thread3245.asp http://www.keil.com/forum/docs/thread3239.asp He reminds you: Before posting, you might ask yourself "Does my question have anything to do with Keil products?"
But if a additional IC is ued,the port could be saved. Now,I'm using a ZLG7189 which is produced by Guangdong Zhouligong in China.It has a I2C-like interface. Only 4 port line is used and tow of them could be shared. And it could scan keyboard automatically,in fact,it could manage 64 keys and 8 7-seg LED. Maybe others are using a better IC.If you let the MCU scan keyboards,it will also take much CPU time.
hi, no way to discuss it. Use port0: 4 bits as output and 4 bits as input (do not forget to add pull-up resistors for last ones). If you search for keyboard management IC especialy then there are some x51 MCUs with such option, for example Atmel's AT89C51RB2/RC2 - they have built-in Keyboard Interrupt Interface. Good days!
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