[quote=bg2cw/7]以前dds3的板子能用吗？[/quote]
it required a few changes from dds 3.xx for pcb deisgn use dds3.xx or dds 2.xx designs
dds 3.xx 的pcb需要很少的修改
changes required in the circuit of dds 3.xx
=====================
1. remove 74ls139 but keep resistor on ra4
2. remove connection on rb1, and rb2 connect these to pic-2 serial port
3. disconnect lcd pin 4 (rs) from sw3..sw6 common, and connect to ra6
4. connect sw3..sw6 (i.e. rit/ssb/step/cal) common to ra7
done!.
pic 2 connections
=================
1. connect pic 2 serial to pic 1 serial port, i.e. rb1 to rb1 and rb2 to rb2
2. connect vdd (+5v) on pin 14 and ground (0v) on pin 5
3. connect a pull up resistor on ra4 (4k7) to vdd
band out puts are (pic-2)
=================
rb0 general coverage
rb3 band 1
rb4 band 2
rb5 band 3
rb6 band 4
rb7 band 5
ra6 band 6
ra7 band 7
ra0 band 8
ra1 band 9
mode selection
==============
am - ra4 on pic-1
cw - ra2 on pic-2
lsb - ra3 on pic-2
usb - ra4 on pic-2
ra5 left unconnected
