cbmeeks Posted February 14, 2020 Share Posted February 14, 2020 I'm thinking about wire-wrapping a small TMS9995 board and I have everything except a UART for it. It seems the TMS9902 is the preferred route. But all I have are some 65C51's and some modern NXP DUART's. Before I order a (possibly fake) TMS9902 off eBay...wait two months to arrive from China...discover they are fake....rinse/repeat, I was wondering: 1) Is there a somewhat reliable supplier of them in the US? I only need 1 or 2. 2) How difficult would using a non-standard TI part be? Something like the 65C51. 3) Something different? All I want to do is run a simple serial monitor and tinker around. Thanks for any suggestions. Quote Link to comment Share on other sites More sharing options...
+FarmerPotato Posted February 14, 2020 Share Posted February 14, 2020 I have China 9902s from polida2008 (eBay). I can send you some. I have not tested them yet. You can follow Stuart Connor's design to use any MAX232 (TI even makes them) to make the signal EIA-RS232 levels. Or just get a TTL serial cable ("FTDI") to hook up to the RX/TX/CTS pins. Another idea, which I have not got to yet, is to divide down a 8.192 MHz oscillator and match 115,200 baud exactly. The 9902 with a 3Mhz input can't quite get it. Probably safer though, going with the TMS9995 3 MHz clock out and 9600 baud. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted February 15, 2020 Author Share Posted February 15, 2020 Thanks for the offer. I've bought from polida2008 before but have not tested the chips I got from him. However, I also found a 9902 from a US seller so I went ahead and bought it. Not sure if that makes much difference but he said he got them as new parts a long time ago. Thanks! Quote Link to comment Share on other sites More sharing options...
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