On Sat, 11 Oct 1997 09:31:07 +1300 Gavin Jackson writes: >Hi there > >I am using the BSF instruction to set bits >on PORTD on a 16c74A. The whole port is >configured as output (CLRF TRISD). The >problem is, when I set a bit on the port, any >other bits that were set, clear and then the >bit the instruction specifies, sets. >Why don't the other bits remain set? What we're always warned about, and has caught me once, is to make sure you are not doing a read-modify-write instruction (such as bit set) immediately after a write to the port. The read-modify-write actually reads the port lines, and if they have not yet settled from the previous write, you may get strange results. >I also had a problem getting the serial port >on the 16c74A to work. I tried everything! >It turned out the 2.4576MHz crystal was >not quite accurate enough. One would think >that crystals were supposed to be quite >accurate. I'm also surprised! In general, I believe an asynchronous serial link should work if each end is within 5% of the correct speed. That's awfully far for a crystal to be off unless the crystal was not really controlling the oscillator (some times they kinda take off on their own). I'm using 16 MHz ceramic resonators on the 16c74a and sending/receiving 250 Kbps quite well. > >Great list! > Yes! Harold Harold Hallikainen Voice/fax/bbs +1 805 541 0201 Hallikainen & Friends web http://hallikainen.com PO Box 4737 email harold@hallikainen.com San Luis Obispo, CA 93403-4737 email hhallika@broadcast.net USA email HaroldHallikainen@juno.com email ap621@cleveland.freenet.edu