As your sendcmd() and sendchar() routine both use the chkbusy() routine, I suspect the chkbusy() routine is maybe not what it should be.

You may want to check this: (from the LCD-tutorial on this site)

The EN line is called "Enable." This control line is used to tell the LCD that you are sending it data. To send data to the LCD, your program should first set this line high (1) and then set the other two control lines and/or put data on the data bus. When the other lines are completely ready, bring EN low (0) again. The 1-0 transition tells the 44780 to take the data currently found on the other control lines and on the data bus and to treat it as a command.



regards
Patrick