|
Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference?
Cheers
|
That's like 10% error.? So, 9600 baud becomes 10360 baud.? Should work... only 1 way to find out.
On Friday, April 30, 2021, 05:45:42 a.m. EDT, Zanchius <flavio@...> wrote:
Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference?
Cheers
|
Josh: does your serial code do autobaud - i forget? If so it would probably be fine.
toggle quoted message
Show quoted text
Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference?
Cheers
|
Zanchius wrote: Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference? Hi Flavio, Yes, I'm having trouble getting the 1.8 MHz resonators as well. Mouser quit carrying them, so I bought my last batch from Tayda2009 on ebay. But they seem to have gone out of business. As for the FJN3303 and FJN4303 transistors, I have enough for customers; but shipping to the UK is expensive. The frequency is critical to get the right baud rate. Changing from 1.8 to 2.0 MHz will change the baud rate from 9600 to 1066 baud. It will still work if you can set your Terminal program for such an oddball rate. A better solution is to get a 1.8432 MHz crystal, which is a standard frequency and fairly easy to find. Crystals don't have the internal capacitors, so you'll also need to add two 20pf capacitors, one from each side of the crystal to GND (the schematic in the manual shows these capacitors). Another option is to change the divisor in the 8250 UART. This can compensate for your 2 MHz resonator. But it means changing a byte in the EPROM, and burning another one. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Hi Lee,
I would be comfortable in flipping a byte or two on the EPROM image, I managed to find a programmer that can burn 27256 chips so that also wouldn't be an issue.
May I ask which bytes should be changed?
best
Flavio
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A 10% error is really too big, for serial communications.? It miiiight still work, but I strongly doubt it, because by the time you get to the end of the character (10 bits in - start, 8-data, stop), you're a full bit time off.? Most UARTS use an internal clock that's a multiple of the baud rate - typically 16 times - and do their sample for each bit on what should be the middle of the bit (for example, 8 clocks after the one that detected the start bit).? This means that by the end of the character, it's sampling the wrong bit in the serial stream.
I found that errors of less than 3% usually work; I try to keep the timing error to half that or better if at all possible.? Lee's recommendation of a 1.8432 crystal comes in with an error of about 2.4%, which should work fine.
~~
Mark Moulding
|
Humm ... This adds another gremlin in the equation. I'm starting to regret ordering only the PCBs.
But hey, there isn't any fun without problems to solve. I may have a handful of 1.8432MHz crystal oscillators in my stock so I'll give it a try.
F?
On Fri, 30 Apr 2021, 18:39 Mark Moulding, < mark@...> wrote: A 10% error is really too big, for serial communications.? It miiiight still work, but I strongly doubt it, because by the time you get to the end of the character (10 bits in - start, 8-data, stop), you're a full bit time off.? Most UARTS use an internal clock that's a multiple of the baud rate - typically 16 times - and do their sample for each bit on what should be the middle of the bit (for example, 8 clocks after the one that detected the start bit).? This means that by the end of the character, it's sampling the wrong bit in the serial stream.
I found that errors of less than 3% usually work; I try to keep the timing error to half that or better if at all possible.? Lee's recommendation of a 1.8432 crystal comes in with an error of about 2.4%, which should work fine.
~~
Mark Moulding
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bill rowe wrote: Josh: does your serial code do autobaud - i forget? If so it would probably be fine. No; it doesn't autobaud. But there are two serial ports; one on the Z80-CPU board, and another on the Z80-SIO board. The one on the CPU board uses the 4 MHz resonator; so it will still work. It is fixed at 9600 baud; but would be 4800 baud if you used a 2 MHz resonator, or 19200 if you used 8 MHz etc. The 8250 UART on the Z80-SIO board uses the 1.8 MHz resonator. 18.432 MHz and 3.072 MHz happen to give you all the standard baud rates from 50-38.4Kbaud with negligible error. See the 8250/82C50/16C450 datasheet for details on how to calculate the baud rate constant for various frequencies. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Zanchius wrote: I would be comfortable in flipping a byte or two on the EPROM image, I managed to find a programmer that can burn 27256 chips so that also wouldn't be an issue.
May I ask which bytes should be changed? Hi Flavio, Download the EPROM source file at <> from the website at <>. In the .ASM or .LST file, search for "LD (ACE_BAUD),A". It occurs in two places. The first one sets the initial baud rate to 9600 (with a 1.8 MHz resonator or 1.8432 crystal). Change the byte at 01AE to whatever is correct for your crystal and desired baud rate. 01A5 21 80FF COLD_START LD HL,RC_TYPE 01A8 06 0F LD B,CS_CLR_LEN 01AA CD 100C CALL CLEAR_BLOCK ;DB 0 ;(RC_TYPE) ;DB 0 ;(RC_SOFT) ;DB 0 ;(RC_STEP) ;DB 0 ;(RC_CC) ;DB 0 ;(RC_HALT) ;DB 0 ;(RC_F0) ;DB 0 ;(RC_RST0) ;DB 0 ;(RC_HARD) ;DB 0 ;(RegPtr) ;DW 0 ;(ABUSS) ;DB 0 ;(IoPtr) ;DB 0 ;(RX_ERR_LDRT) ;DB 0 ;(RX_ERR_STOP) ;DB 0 ;(RX_ERR_OVR) 01AD 3E 0C LD A,12 <=== this sets 9600 baud! 01AF 32 8FFF LD (ACE_BAUD),A Or, if you're using the Z80-CPU card serial port, you can change the Z80-SIO card baud rate using this call: 080B CD CA0D PORT_SPEED CALL PRINTI 080E 0D0A2830 433D3936 DB CR,LF,"(0C=9600) BAUD:",EOS 0816 30302920 42415544 081E 3A00 0820 3A 8FFF LD A,(ACE_BAUD) 0823 CD F60D CALL PUT_BYTE 0826 CD 490D CALL SPACE_GET_BYTE 0829 D8 RET C 082A 32 8FFF LD (ACE_BAUD),A 082D CD F214 CALL ACE_SET_BAUD 0830 C9 RET Hope this helps! Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Zanchius wrote: Humm ... This adds another gremlin in the equation. I'm starting to regret ordering only the PCBs.
But hey, there isn't any fun without problems to solve. I may have a handful of 1.8432MHz crystal oscillators in my stock so I'll give it a try. That will work. 1.8432 MHz hits 9600 baud exactly. The 1.80 MHz resonator is actually 2.4% low (but it works anyway). Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Lee,
That's brilliant! Thank you for the information.
And thank you everyone for your help as well.
Now the wait for the boards to arrive...
(+_+)
Flavio
Zanchius wrote:
> Humm ... This adds another gremlin in the equation. I'm starting to
> regret ordering only the PCBs.
>
> But hey, there isn't any fun without problems to solve. I may have a
> handful of 1.8432MHz crystal oscillators in my stock so I'll give it a try.
That will work. 1.8432 MHz hits 9600 baud exactly. The 1.80 MHz
resonator is actually 2.4% low (but it works anyway).
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? ?-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377,
--
This email has been checked for viruses by Avast antivirus software.
|
You can order direct from Tayda Electronics, and they *are* stocked (3,988,888 parts claimed).
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Lee Hart Sent: Friday, April 30, 2021 12:04 PM To: [email protected]Subject: Re: [Z80MC] SD I/O 1.8MHz resonator Zanchius wrote: Good morning all,
This is proving to be another hard to find component, so I got a 2MHz
one instead. If I understood correctly there's a direct correlation with
the terminal baud rate provided by the UART. Would 200KHz make much
diference? Hi Flavio, Yes, I'm having trouble getting the 1.8 MHz resonators as well. Mouser quit carrying them, so I bought my last batch from Tayda2009 on ebay. But they seem to have gone out of business. As for the FJN3303 and FJN4303 transistors, I have enough for customers; but shipping to the UK is expensive. The frequency is critical to get the right baud rate. Changing from 1.8 to 2.0 MHz will change the baud rate from 9600 to 1066 baud. It will still work if you can set your Terminal program for such an oddball rate. A better solution is to get a 1.8432 MHz crystal, which is a standard frequency and fairly easy to find. Crystals don't have the internal capacitors, so you'll also need to add two 20pf capacitors, one from each side of the crystal to GND (the schematic in the manual shows these capacitors). Another option is to change the divisor in the 8250 UART. This can compensate for your 2 MHz resonator. But it means changing a byte in the EPROM, and burning another one. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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You could cheat and just use the original part:?
You'll probably have to wait a few weeks, however :-{.
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No, it is very tight on timing so that it can do full duplex bit bang.? But that runs on the 4Mhz Z80.? The 1.8Mhz is for the UART.
On Friday, April 30, 2021, 11:41:09 a.m. EDT, bill rowe <bill_rowe_ottawa@...> wrote:
Josh: does your serial code do autobaud - i forget? If so it would probably be fine.
Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference?
Cheers
|
The 8250 has a coarse divider for baud rate.?
12 works to divide 1,843,200 to 9600 baud because
1843200 / 12 / 16 = 9600
The next divider number is 13 and to get 9600 at that value you would need...
X / 13 / 16 = 9600
Solve for X = 1,996,800? ?(so 2Mhz would be pretty decent)
2Mhz gives 9615, = 0.2% error
But, as pointed out, 1.8 is available and 1.8432 crystals will also work (adding the loading caps).
On Friday, April 30, 2021, 04:22:10 p.m. EDT, Lee Hart <leeahart@...> wrote:
Zanchius wrote:
> I would be comfortable in flipping a byte or two on the EPROM image, I
> managed to find a programmer that can burn 27256 chips so that also
> wouldn't be an issue.
> May I ask which bytes should be changed?
Hi Flavio,
Download the EPROM source file at
<> from the website at
<>.
In the .ASM or .LST file, search for "LD (ACE_BAUD),A". It occurs in two
places. The first one sets the initial baud rate to 9600 (with a 1.8 MHz
resonator or 1.8432 crystal). Change the byte at 01AE to whatever is
correct for your crystal and desired baud rate.
01A5? 21 80FF??? COLD_START??? LD??? HL,RC_TYPE
01A8? 06 0F??? ??? ??? LD??? B,CS_CLR_LEN
01AA? CD 100C??? ??? ??? CALL??? CLEAR_BLOCK
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_TYPE)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_SOFT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_STEP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_CC)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HALT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_F0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_RST0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HARD)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RegPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DW??? 0??? ;(ABUSS)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(IoPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_LDRT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_STOP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_OVR)
01AD? 3E 0C? ??? ??? ??? LD??? A,12 <=== this sets 9600 baud!
01AF? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
Or, if you're using the Z80-CPU card serial port, you can change the
Z80-SIO card baud rate using this call:
080B? CD CA0D? ? ? ? ? PORT_SPEED??? CALL??? PRINTI??? ???
080E? 0D0A2830 433D3936 ??? ??? DB??? CR,LF,"(0C=9600) BAUD:",EOS
0816? 30302920 42415544
081E? 3A00
0820? 3A 8FFF? ? ? ? ? ??? ??? LD??? A,(ACE_BAUD)
0823? CD F60D? ? ? ? ? ??? ??? CALL??? PUT_BYTE
0826? CD 490D? ? ? ? ? ??? ??? CALL??? SPACE_GET_BYTE
0829? D8? ? ? ? ? ? ? ? ??? ??? RET? C
082A? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
082D? CD F214? ? ? ? ? ??? ??? CALL??? ACE_SET_BAUD
0830? C9? ? ? ? ? ? ? ? ??? ??? RET
Hope this helps!
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? -- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
--
This email has been checked for viruses by Avast antivirus software.
|
Thank you Josh, this is very useful.
Flavio
On Sat, 1 May 2021 at 12:07, joshbensadon via <joshbensadon= [email protected]> wrote:
The 8250 has a coarse divider for baud rate.?
12 works to divide 1,843,200 to 9600 baud because
1843200 / 12 / 16 = 9600
The next divider number is 13 and to get 9600 at that value you would need...
X / 13 / 16 = 9600
Solve for X = 1,996,800? ?(so 2Mhz would be pretty decent)
2Mhz gives 9615, = 0.2% error
But, as pointed out, 1.8 is available and 1.8432 crystals will also work (adding the loading caps).
On Friday, April 30, 2021, 04:22:10 p.m. EDT, Lee Hart < leeahart@...> wrote:
Zanchius wrote:
> I would be comfortable in flipping a byte or two on the EPROM image, I
> managed to find a programmer that can burn 27256 chips so that also
> wouldn't be an issue.
> May I ask which bytes should be changed?
Hi Flavio,
Download the EPROM source file at
<> from the website at
<>.
In the .ASM or .LST file, search for "LD (ACE_BAUD),A". It occurs in two
places. The first one sets the initial baud rate to 9600 (with a 1.8 MHz
resonator or 1.8432 crystal). Change the byte at 01AE to whatever is
correct for your crystal and desired baud rate.
01A5? 21 80FF??? COLD_START??? LD??? HL,RC_TYPE
01A8? 06 0F??? ??? ??? LD??? B,CS_CLR_LEN
01AA? CD 100C??? ??? ??? CALL??? CLEAR_BLOCK
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_TYPE)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_SOFT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_STEP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_CC)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HALT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_F0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_RST0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HARD)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RegPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DW??? 0??? ;(ABUSS)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(IoPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_LDRT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_STOP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_OVR)
01AD? 3E 0C? ??? ??? ??? LD??? A,12 <=== this sets 9600 baud!
01AF? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
Or, if you're using the Z80-CPU card serial port, you can change the
Z80-SIO card baud rate using this call:
080B? CD CA0D? ? ? ? ? PORT_SPEED??? CALL??? PRINTI??? ???
080E? 0D0A2830 433D3936 ??? ??? DB??? CR,LF,"(0C=9600) BAUD:",EOS
0816? 30302920 42415544
081E? 3A00
0820? 3A 8FFF? ? ? ? ? ??? ??? LD??? A,(ACE_BAUD)
0823? CD F60D? ? ? ? ? ??? ??? CALL??? PUT_BYTE
0826? CD 490D? ? ? ? ? ??? ??? CALL??? SPACE_GET_BYTE
0829? D8? ? ? ? ? ? ? ? ??? ??? RET? C
082A? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
082D? CD F214? ? ? ? ? ??? ??? CALL??? ACE_SET_BAUD
0830? C9? ? ? ? ? ? ? ? ??? ??? RET
Hope this helps!
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? -- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377,
--
This email has been checked for viruses by Avast antivirus software.
-- Flavio V. S. Zanchi
flavio@...
"Egal, wie dicht du bist, Goethe war Dichter"
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Hi folks!
Just a quick update, it actually works if your terminal client supports custom baud rates. I got my kit fully assembled this morning, and had it working? in no time using GtkTerm under Linux, may work in Putty as well, but I haven't tried yet.
Thanks? for all the help.
|
FYI: for non-standard baud rates;
I use Linux for all development work and?a USB-2-TTL serial converter for serial I/O. I tested with with CH340 to see how much baud-rate error would be tolerated at 57.6Kb and found up to +7% error was still functional but +10% was no-joy. I also found that anything more than -2% was no-joy.
I use PICOCOM for terminal emulation, which allows one to use ANY baud rate you tell it, so if you are using a 2 MHz oscillator, simply tell PICOCOM your ACTUAL baud rate is 62.5Kb (or whatever) and it'll work. Not sure about WINDOWS terminal emulators. Try it and see.?
Peace and blessings.
|
glad it's working for you.? Did you try other fixed baud rates?
toggle quoted message
Show quoted text
FYI: for non-standard baud rates;
I use Linux for all development work and?a USB-2-TTL serial converter for serial I/O. I tested with with CH340 to see how much baud-rate error would be tolerated at 57.6Kb and found up to +7% error was still functional but +10% was no-joy. I also found that
anything more than -2% was no-joy.
I use PICOCOM for terminal emulation, which allows one to use ANY baud rate you tell it, so if you are using a 2 MHz oscillator, simply tell PICOCOM your ACTUAL baud rate is 62.5Kb (or whatever) and it'll work. Not sure about WINDOWS terminal emulators. Try
it and see.?
Peace and blessings.
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SCOTT VITALE wrote: FYI: for non-standard baud rates;
I use Linux for all development work and?a USB-2-TTL serial converter for serial I/O. I tested with with CH340 to see how much baud-rate error would be tolerated at 57.6Kb and found up to +7% error was still functional but +10% was no-joy. I also found that anything more than -2% was no-joy.
I use PICOCOM for terminal emulation, which allows one to use ANY baud rate you tell it, so if you are using a 2 MHz oscillator, simply tell PICOCOM your ACTUAL baud rate is 62.5Kb (or whatever) and it'll work. Not sure about WINDOWS terminal emulators. Try it and see. Thanks Scott, The terminal programs I normally use (ProComm and TeraTerm) don't support odd baud rates; I'll have to try the one you suggested. It sounds like a good tool for testing baud rate accuracy. I did find a source for more 1.8 MHz resonators. I ordered directly from Tayda Electronics in Thailand, and they arrived. :-) Best wishes, Lee Hart -- We cannot solve our problems with the same thinking we used when we created them. -- Albert Einstein -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Zanchius
Lee Hart