cbmeeks #1 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 Share this post Link to post Share on other sites
+FarmerPotato #2 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 Share this post Link to post Share on other sites
cbmeeks #3 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 Share this post Link to post Share on other sites