== How to build a RS232 - Interface for the CPC-Series!==- === Schematic and source code.===
First about the connection plan: You need a power supply that supports +9V,-9V and 5V. Connect all pins. You have to connect D0..D7 from the adressbus with the Z80 STI. You have to connect D0 with pin 21, D1 with pin 22, ..., D7 with pin 28. That's all.
WARRANTY: There is no warranty of any defects of your CPC!!! On my CPC everything works fine and I hope that you won't have any problems with this RS232-Interface.
Second part: How to program the interface. (The assembler code is saved in RS232.ASM)
Z80-STI: 50 to 19200 bps (5,6,7 or 8 bit, 1, 1 1/2, 2 stopb., all parity flags) 24 registers, use 16 registers (direct) with F8E0-F8EF, the last 8 registers can be used indirect with a special register
== About the assambler assembler code:=========================
The program RS232.ASM installs 2 new BASIC commands (|FORMAT, |RECORD, |SEND).
Here you can read the description about this new commands:
'''|FORMAT''', number of bps, number of stop-bits, data bits, parity on/off, parity even/odd
Number of bps: 0 = 50 bps
1 = 75 bps
2 = 110 bps
'''|RECORD''', @a$
The incoming chars will be read in a string. Control codes will be send to the
string, too, because sometimes you need it for binary transmissions.
'''|SEND''', @a$
The string is send until it ends, except you press ESC. The program will not
send CR or LF, so you can use this for binary transmission.
== Last words:===========
This interface is described in the book "Maschinenspracheprogramm und Hardware-
Tim Riemann
Gartenweg 3
35114 Haina-Kloster
Germany
eMail: TCS-Software@t-online.de
Third part: == Used components:==
1-Z80-STI (or MK 3801-4)
1-SN 75189
1-SN 75188
1-74 LS 30
1-74 LS 138
1-74 LS 20
1-74 LS 04
1-74 LS 32
1-25pin SUB-D connector (male)
1-connector for the expansion port
== Downloads ==
* [[File:Rs232cpc.lzh]] - All info and files on topic