Welcome, Guest. Please login or register.


Author Topic: Good edge connectors and cables. (Read 4257 times)

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #30 on: 2017.May.21. 21:26:53 »
The first  word is the bit-rate, and the third byte is the wait-state, they must change accordingly but not less than 1, I think.

The bit-rate has added 243 or 244 as a constant.


So 19200 baud would be more or less 251(00FBh, 01h), and 38400 would be 246(00F6h ,01h).

Midi(31250 baud) is between them, approximately 248(00F8h, 01h).

Some technical instrument must be used to probe this....
« Last Edit: 2017.May.22. 12:39:09 by gflorez »

Offline Zozosoft

  • EP addict
  • *
  • Posts: 12981
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 53.0 Firefox 53.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Good edge connectors and cables.
« Reply #31 on: 2017.May.22. 22:16:09 »
Code: ZiLOG Z80 Assembler
  1. ;--------------------------------DATA SECTION----------------------------------
  2. ;
  3. ;       Table of Baud Delays (0 - 15) CALIBRATED FOR 8MHz CRYSTAL
  4. ;        16-bit baud delay counter, 8-bit middle-of-bit sync counter
  5. ;
  6. SECOND:
  7. BAUD_TABLE:     DW      1240H                   ;    50 Baud
  8.                 DB      0FFH
  9.                 DW      0CA0H                   ;    75  ..
  10.                 DB      0FFH
  11.                 DW      08C8H                   ;   110  ..
  12.                 DB      0FFH
  13.                 DW      0760H                   ; 134.5  ..
  14.                 DB      0FFH
  15.                 DW      06C0H                   ;   150  ..
  16.                 DB      0FFH
  17.                 DW      0548H                   ;   200  ..
  18.                 DB      0C0H
  19.                 DW      03D0H                   ;   300  ..
  20.                 DB      80H
  21.                 DW      0265H                   ;   600  ..
  22.                 DB      40H
  23. BAUD_DEFAULT:   DW      01AAH                   ;  1200  ..
  24.                 DB      20H
  25.                 DW      0169H                   ;  1800  ..
  26.                 DB      18H     ;*
  27.                 DW      014CH                   ;  2400  ..
  28.                 DB      10H
  29.                 DW      012CH                   ;  3600  ..
  30.                 DB      9       ;*     
  31.                 DW      011DH                   ;  4800  ..
  32.                 DB      6
  33.                 DW      010EH                   ;  7200  ..
  34.                 DB      2       ;*
  35.                 DW      0106H                   ;  9600  ..
  36.                 DB      1
  37.                 DW      0106H                   ;  9600  ..
  38.                 DB      1

The problem is: Enterprise serial port are fully software driven. And the 4MHz Z80 are too slow for higher rates. At the "middle-of-bit sync counter" need 0.5 value for 19200 baud... probably this is the reason why got the Modell 911 a hw serial port with SIO chip (it is expensive, when all other parts of the machine are cost reduced).

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #32 on: 2017.May.22. 22:48:43 »
Ah, ok, now I understand you. I though that the third bit was only a pause.  The routine is not very efficient.

On the other side, 9600 bauds can still serve me to connect the ESP8266 module.

Thanks.

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #33 on: 2017.May.28. 13:48:49 »
Maybe a new Serial/Net  device must be created(but I have not the skills).

On the BBC scene, they have UPURShttp://www.retro-kit.co.uk/UPURS/, a software driven serial port software that converts the User Port on to a complete RS-232 at 115K baud, all achieved with only a 2Mhz 6502 processor and few modifications on the cable.


18008-0

The BBC also has a RS-423 serial port, but I don't know if it is software driven like the Enterprise one.
.

With it they can load disk images or any type of file.

The driver can be loaded like an application or like a Rom.
« Last Edit: 2017.May.28. 17:57:04 by gflorez »

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #34 on: 2017.June.21. 08:30:33 »
As you know I own two Enterprises with exactly the same add-ons, Saint 1MB internal Ram cards and  20Mhz CMos  Z80 processors with selectable speeds 4Mhz and 10Mhz.

If I connect them with the NET cable, they work as expected, but if I connect a stock EP128K to one of my modified computers at 4Mhz, the NET refuses to work at all.

As the Serial/Net is software driven, can it be the memory different speeds the problem with the connection?
« Last Edit: 2017.June.21. 10:33:38 by gflorez »

Offline Zozosoft

  • EP addict
  • *
  • Posts: 12981
  • Country: hu
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Good edge connectors and cables.
« Reply #35 on: 2017.June.21. 09:27:30 »
If the upgraded computer have a EXOS 2.4 then it is disable the memory wait states at default. Try SET 191,4

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #36 on: 2017.June.21. 10:01:31 »
Ok, thanks. I have read you about it before, but never though it would make a difference so big.

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Linux Linux
  • Browser:
  • Firefox 59.0 Firefox 59.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #37 on: 2018.April.08. 11:00:58 »
A Spanish friend, Dandare, creator of the Dandanator for the Spectrum range, has aided me to interface the Enterprise serial port to serial ttl, for example to an USB to TTL adapter based on the CH340G chip, that allows handshakes. The main intention is to interface an ESP-8266 Wifi module.



This is my humble prototype:



At last it worked without the two optocouplers at the right.
« Last Edit: 2018.April.08. 11:09:51 by gflorez »

Online gflorez

  • EP addict
  • *
  • Posts: 2330
  • Country: es
  • OS:
  • Windows XP Windows XP
  • Browser:
  • Firefox 52.0 Firefox 52.0
    • View Profile
Re: Good edge connectors and cables.
« Reply #38 on: 2018.April.16. 13:18:31 »
Usually the Wifi modules work at 3,3v TTL, so the optional LM1117 will feed the pull-ups and the module.


------

I have made a simple Basic program to talk with a PC, I can write forward, but I have problems receiving.

The GET command gets stuck if there is no incoming character. So, before reading the serial port I test bit 5 of Z80 port 0B6h(182) for incoming data. But this port is a "general purpose" one, and is corrupted by other drivers that write on it.

Long time ago Zozo answered me a tip to overcome this situation, but I don't remember on what thread.

Please, can you kindly repeat me the way to properly read the "Status in" bit?

Thanks.
« Last Edit: 2018.April.16. 15:02:18 by gflorez »