verbist@esat.kuleuven.ac.be (07/31/90)
Hi, This might be of interest for some amateurs using the HAPN-plug-in modem card. The HAPN driver is supported by NOS but generates some false Tx-interrupts. I received the following reply from VK3BLW. It learns you how to fix the card so that no false Tx-interrupts occur anymore ... and it works !!! 73 de Patrick, ON1AML +===============================+====================================+ | Patrick Verbist | Email: verbist@esat.kuleuven.ac.be | | Catholic University of Leuven | ~~~~~~ | | Electrical Engineering Dep. | PACKET: ON1AML@ON7RC | | Kardinaal Mercierlaan 94 | ~~~~~~~ | | B-3030 LEUVEN | Tel: ++32 16 220931 (ext. 1152) | | | ~~~~ | | BELGIUM - EUROPE | | +===============================+====================================+ >ON1AML @ON7RC de:VK3BLW 10.06.90 10:46 UTC 2516 Bytes >HAPN Card Fix > > >900609/0602z ON6AR , 900608/2157 PI8HWB, 900508/0826z PI8HWB >900608/0819 PA3EAE, 900607/2231 PA0SCH, 900606/1840z SV1IW. >900606/1113z YB5QZ., 900606/0810z DU1EAG, 900605/0047z VK4BBS >900604/0816L VK2OP., 900603/1555z VK2EHQ, 900603/2221l VK3RPA >900603/2222z VK3BLW > >Hi Patrick, I saw your message re your HAPN problems on INTERNET, this is >a fix that was generated locally here in Melbourne, Australia by Richard >VK3DRU, it is used quite successfully here in Melbourne on KA9Q TCPIP, >hope it also works for you. I have sent you this both via Packet and >via Internet would be interested to know if you get either or both >Bryan >VK3BLW >Here is Richards message relating to the fix >-------------------------------------------------------------------------- >Date: Sat, 14 Jan 89 21:20:43 GMT >Message-Id: <4@vk3dru> >From: richard@vk3dru (Richard Urmonas) >To: all%tcpip@vk3rpa-1 >Subject: HAPN board false Tx >As all users of tcpip on the HAPN board will know a problem occurs with false >Tx startups. Investigating this problem shows that a pulse occurs on the 8273 >RTS line. (estimated at < 100 ms). After some experimentation a workable >solution is as follows: >- Remove U12 (74LS221) from socket bend pin 1 out and reinsert (if chip >soldered in cut leg near board and bend out. >- Solder a link from pin 1 to pin 8 (i.e. ground pin) on the actual chip (not >the PCB), be careful not to get solder in the socket ! >- On the underside of the board cut track going to pin 2 of U12. >- Solder a jumper from pin 2 of U12 to U11 (XR2206) pin 10. >This fix filters out the short pulse on RTS which triggers the Tx monostables. >The other trigger input of the monostable must be used as it accepts slow >risetime waveforms. So far I have not noticed any false Tx from my board. >I would be interested in hearing if the fix does not work on someones board >(and hence a better fix is needed).