As the Arduino will not operate at 110 baud I made a simple interface with PIC16F690 which will input at 110 baud and output to the Arduino monitor screen at 19200 baud. Further information on request.
Which Arduino?
Out of curiosity, why do you need such a low baudrate?
I think you’re missing something here…
You’re asking for help, not us.
Perhaps add some background to your project
Skill level, schematic, existing code etc.
I would like to see a schematic and the code.
How did you connect this to an ASR33?
Arduino UNO R3
An Uno R3 does support 110 baud.
void setup()
{
Serial.begin(110);
Serial.println("hello world");
}
void loop()
{
Serial.println(millis());
delay(1000);
}
Output (using PuTTY)
hello world
0
999
1999
3000
3999
5000
6000
7001
8001
9000
10001
11001
12002
13001
14002
15002
16003
17003
18003
19003
20003
21004
22004
23005
24004
25005
26005
27005
28006
29005
Sorry , I should have said the Arduino Serial Monitor does not support 110 baud and I am not sure it works below 600 baud.
ASR33 operates at 110 baud.
What am I not getting here? If the need is to interface to a 110 baud device and output to the arduino serial monitor, why the PIC? Why not just input to the arduino at 110 baud on one serial port and have it print to the serial monitor at whatever speed you want using the other serial port?
Pardon me, but I feel like I’m missing something obvious here…
The Uno only has one hardware UART 
But SoftwareSerial (or AltSoftSerial or NeoSWSerial) might provide a solution; not sure if low baudrates are supported with those.
And obviously a board with a UART port that is not used for communication with the PC (e.g. Mega, Leonardo, Micro, Nano Every, SparkFun Pro Micro).
On my installation, the Arduino serial monitor accepts 300 baud to 921600 baud. I am perhaps missing something?
No, you're not missing something; there is no 110 baud in the Arduino IDE. But I think that we're missing the bigger picture of your project.
An ASR33 is an old teletype terminal which works with paper tape IIRC.
They are 50+ years old, sort of electrified typewriter.
(always thought a VT100 was cool …)
The device works with 110 baud as I expect that was the highest baud rate possible as the machine was/is electromechanical. Don’t know if they were ASCII-ish, the number of bits they use etc.
I used an ASR33 with my first SWTPC computer. Paper tape and a non co-resident editor assembler made for a long day. Mine had an acoustic modem I connected to the uni IBM360 from home as well.
So what about the PIC schematic and the code?
@kswells
My ASR33 had a current loop interface using an optocoupler. Sounds like yours is a little fancier.
That came in all ways! MY first use was in a university class using GE time sharing. Had one connected as current loop to my SYM-1 single board computer.
I don't think so... Not unless you also lower the CPU clock rate...
BAUD = F_CPU/(8*(UBRR+1)) = 16000000(4096) = 3900bps
recently connected to an ASR33 using a ESP32 with TTL-RS232 interface at 110baud
received and transmitted some characters OK
some characters faulty due to mechanical pulse generator in the ASR33
it is difficult these days to find engineers who can repair ARS33s