good lord - what a wonderful thing. Congrats.
From: firstname.lastname@example.org <email@example.com> on behalf of Jeff Truck <jeff.truck@...>
Sent: October 3, 2019 12:08 AM
To: firstname.lastname@example.org <email@example.com>
Subject: [cosmacelf] Frankenstein UART Board
Another creation. Uses the 1854 UART in Mode 1. IO Group 02.
OUT4: configure interval counter
OUT5: set interval counter initial count.
OUT7: set UART control register.
IN7: read UART status register.
OUT6: send byte.
IN6: receive byte.
/EF2 is /DA
/EF3 is /THRE
Uses a 3.6864 MHz oscillator to derive baud rates of 300,1200,2400,4800,9600,14400,19200,28800,38400,57600,115200. I have tested the 115200 but at that speed with Frankie running at 4MHz I had to add some delay in the program to prevent overrun.
Very fun to build.
2k EEPROM programmed to control the UART and the programmable interval timer control lines. A 74HC138 decodes the N lines to set one of six utilized ports as an address to the EEPROM. The 82C54 is in itself an interesting little chip. I use mode 3.
The 1854 can be found at Jameco. Mine is date stamped 745.
Yes I cheated slightly by using a FTDI chip for USB connection to my home computer. It is connected to TX RX /CTS and /RTS on the 1854.
Frankie’s main board IO for data display, keypad and video on/off was converted over to IO GROUP 01.
Olduino - an arduino for the first of us