[E3-hacking] About connecting to the serial on the E3

David Given dg at cowlark.com
Wed Apr 3 23:37:08 BST 2019 

Oh yeah, there's more information here.
http://www.earth.li/~noodles/hardware-e3.html

On Thu, 4 Apr 2019 at 00:36 David Given <dg at cowlark.com> wrote:

> Okay, so this is unclear. That article's talking about connecting the
> emailer via actual RS232 via a TTL-to-RS232 level converter. Nobody does
> this any more; instead you use a USB TTL serial adapter. But it sounds like
> the emailer's output levels are inverted, so logic 1 is 0V and logic 0 is
> 5V.
>
> I have no memory of this whatsoever --- but this was years ago.
>
> *Don't* connect the emailer directly to a RS232 port. You'll fry it.
> RS232 voltages are +/- 12V and are way too high. (I killed mine that way.)
>
> I definitely had the thing working with the cable pictured on my website,
> but I have no idea whether that chip emits inverted signals or not. I'm
> afraid you'll just have to try it and see what happens.
>
>
> On Wed, 3 Apr 2019 at 22:41 Nick Griffin <span1922 at live.com> wrote:
>
>> There is 2 reason why I want to do this..
>> 1.) So I can find a way to restore its services and be able to use it
>> like a normal phone and maybe more.
>> 2.)I have a Amstrad Emailer Plus(E2) too, Its has the Configuration
>> Change on it, if I can back up its Nan then I can share the back up who
>> want to get there's working that's deactivated(Locked) and be able to use
>> it like a normal phone too.. 😊
>>
>> I have a go at getting it working tomorrow.
>>
>> Spanner..
>>
>> *From:* Nick Griffin <span1922 at live.com>
>> *Sent:* ‎Wednesday‎, ‎3‎ ‎April‎ ‎2019 ‎20‎:‎52
>> *To:* Discussion of the Amstrad E3 emailer hardware/software
>> <e3-hacking at earth.li>
>>
>> OK, thanks, I was looking at this site..
>> http://www.cambridgewargames.org.uk/members/andy/emailer/
>> <https://eur03.safelinks.protection.outlook.com/?url=http://www.cambridgewargames.org.uk/members/andy/emailer/&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308605202&sdata=zDMBbvlEKuNMEGdkRXFdUSmjFj/tSiXcoAokoZGATkw%3D&reserved=0>
>>
>> It says on here 3.3v device so was guessing it would work but I don’t
>> understand the inverting the TX Line, would I need to do that with this..?
>> I was reding this…
>>
>> ”Amstrad emailer E3 serial port (18/01/06)
>>
>> A fair bit of confusion exists on the serial port of the E3 with some
>> sources saying a line driver chip is needed, and other saying one is not
>> needed, to connect this to a PC.
>>
>> I've spent a bit of time looking at this and can now offer some
>> explanation. A normal RS232 port will transmit a digital 1 as a negative
>> voltage, usually at least -5V. A 0 is transmitted as a positive voltage,
>> typically at least +5V. The emailer does *not* do this. Using a rather
>> old poorly calibrated scope it appears to actually transmits either 0V or
>> +5V.
>>
>> Now some serial ports will probably accept this, but a 0V input is not a
>> logical anything as far as the RS232 spec is concerned. So your PC, like
>> mine, may ignore this. The fact that this works for some peoples PCs
>> implies it is transmitting a logical 1 as 0v and a logical 0 as +5V.
>>
>> A typical RS232 line driver expects a logical 0 to be 0v and a logical 1
>> to be +5v (or +3.3V if using a 3.3v device). So you end up with an inverted
>> RS232 data and like me and see horrible gibberish on hyperterminal
>>
>> Now, to get a boot log you need to invert the TX signal from the E3 (I
>> used a 74HC04) then pass this to a line driver chip. The only line driver
>> chip I had to hand was a MAX3233E, which is a 3.3 volt part. For this
>> reason I ran both chips from 3.3V and placed a 100ohm resistor between the
>> E3's TX pin nad the input to the inverter. Some logic families get very
>> upset if you exceed the supply voltage on an input by more than about
>> 0.6v... The series resistor limits the current and is a paranoia measure,
>> quicker than looking up the datasheet :-) Anyway, it was a horrible quick
>> bodge but it worked.
>>
>> Here is the output captured from hyperterminal *boot.txt*
>> <https://eur03.safelinks.protection.outlook.com/?url=http://www.cambridgewargames.org.uk/members/andy/emailer/boot.txt&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308625218&sdata=OUBqGj0EApDvIHRdhvvmZg35n7k6/Dr9tadAv5z%2BzGc%3D&reserved=0>
>>  settings were 115,200 8n1 no handshaking.
>>
>> I'll try and post up a diagram of something better in the next few days.
>> I've also built something for the reverse direction but havent had a chance
>> to work out if its working yet....”
>>
>> I do have one made by FTDI too a FTDI FT232RL FT232 USB to TTL 5v 3.3v
>> serial adaptor that has 3.3 v and 5v, it has a jumper to change voltage on
>> RX Line, what about that one..?
>> https://www.xcluma.com/ftdi-ft232rl-ft232-usb-to-ttl-5v-3.3v-serial-adaptor-for-arduino
>> <https://eur03.safelinks.protection.outlook.com/?url=https://www.xcluma.com/ftdi-ft232rl-ft232-usb-to-ttl-5v-3.3v-serial-adaptor-for-arduino&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308635223&sdata=m4ppt5/iAq8M6841kX3u3si/KxGiO5JzCWse1n5xmoU%3D&reserved=0>
>> There is no info on using one of theses because in 2006 they didn’t
>> exsits.. 😊
>> They exist now because of Raspberry PI and Arduino, The Amstrad Emailer
>> uses a singer board computer inside it, The RPI and Arduino are what has
>> become of the technology the Emailer uses. The mini consoles use the
>> technology too.
>>
>> Spanner..
>>
>> *From:* David Given <dg at cowlark.com>
>> *Sent:* ‎Wednesday‎, ‎3‎ ‎April‎ ‎2019 ‎19‎:‎57
>> *To:* Discussion of the Amstrad E3 emailer hardware/software
>> <e3-hacking at earth.li>
>>
>> RS232 is actually +/- 12V! My recollection is that the E3 runs at 0V/5V
>> (I described it as TTL back in 2003). A 3.3V serial converter might work, I
>> couldn't say.
>> On Wed, 3 Apr 2019 at 20:52 Nick Griffin <span1922 at live.com> wrote:
>>
>>> On your site..
>>> “In order to talk to the E2, you need the appropriate cable.
>>> Irritatingly, while the E2 has a serial port, it runs at TTL line levels
>>> not RS232 levels. This means that if you're going to connect it to a PC,
>>> you need a line level converter”
>>>
>>> So I can use a CPC 2102 USB to TTL serial converter because its a line
>>> level converter… 😊 and its RX line is 3.3 volt, this can’t take 5
>>> volts because it could blow the UART0…?
>>>
>>> Spanner..
>>>
>>> *From:* David Given <dg at cowlark.com>
>>> *Sent:* ‎Wednesday‎, ‎3‎ ‎April‎ ‎2019 ‎18‎:‎52
>>> *To:* Discussion of the Amstrad E3 emailer hardware/software
>>> <e3-hacking at earth.li>
>>>
>>> I've got a tool which speaks the PBL protocol and will let you read and
>>> write the flash: http://cowlark.com/amstrad/
>>> <https://eur03.safelinks.protection.outlook.com/?url=http://cowlark.com/amstrad/&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308645228&sdata=N6frWE0wYMl19JThGTV17ul8SQlXYtAXFbGXUwOYfkg%3D&reserved=0>
>>>
>>>
>>> It's also got details of the serial pinout.
>>>
>>> On Wed, 3 Apr 2019 at 19:07 Nick Griffin <span1922 at live.com> wrote:
>>>
>>>> As far as I know when you connect this to serial you don’t get a
>>>> console, like if you connect TheC64 Mini to Putty using a CPC 2102 USB to
>>>> TTL serial convertor, you can log on with your root user and password so
>>>> you can add files, change games and edit files and that ,TheC64 Mini uses
>>>> Uboot to boot up with not PBL so it must be the PBL that's stopping the
>>>> console coming up so if we could hack the PBL (Primary Boot Loader) and
>>>> keep the firmware on the NAND so its still boots up with Amstrad E3 logo
>>>> and that, we need to see the system files and see what can be changed. PBL
>>>> is on the NOR Flash and the Kernel and System is on the NAND Flash. I don’t
>>>> know anything about PBL so we need someone who does.it
>>>> <https://eur03.safelinks.protection.outlook.com/?url=http://does.it&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308655245&sdata=8UZdLqM5pNVmuKUId0Z6DfzP%2BfN8nRfg4Bldo1cYYP0%3D&reserved=0>
>>>> all most works the same as TheC64 Mini,(Its a small Commodore 64, Mini
>>>> Console, its here.. https://www.c64-wiki.com/wiki/THEC64Mini
>>>> <https://eur03.safelinks.protection.outlook.com/?url=https://www.c64-wiki.com/wiki/THEC64Mini&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308665244&sdata=jDpZ%2BY8H9VejOHHIyT6bgRDRgoqh0HKMYultFQdX6%2BU%3D&reserved=0>)
>>>> The mini has 2 partitions, One for Uboot and other for the Kernel and
>>>> System. but only has one chip, NAND Flash, its made by Toshiba too.. 😊.
>>>> Amstrad E3 has 2 chips NOR and NAND Flash. and is using a different Boot
>>>> loader.
>>>>
>>>> Oh.. Can I use my CPC 2102 USB to TTL serial converter to connect to
>>>> the serial on the E3..? this is a pic of it here..
>>>> *https://sc02.alicdn.com/kf/HTB11eb9PFXXXXcLaXXXq6xXFXXXd/CP2102-USB-2-0-to-TTL-UART.jpg_350x350.jpg*
>>>> <https://eur03.safelinks.protection.outlook.com/?url=https://sc02.alicdn.com/kf/HTB11eb9PFXXXXcLaXXXq6xXFXXXd/CP2102-USB-2-0-to-TTL-UART.jpg_350x350.jpg&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308675255&sdata=jgPvSV2Dt5JyFTBhUCKufS2xOPxdlwNSriXHkTnmgQ4%3D&reserved=0> I
>>>> have used it on my TheC64 Mini and my Gotek Drive.
>>>>
>>>> Spanner..
>>>> _______________________________________________
>>>> e3-hacking mailing list
>>>> e3-hacking at earth.li
>>>> https://www.earth.li/mailman/listinfo/e3-hacking
>>>> <https://eur03.safelinks.protection.outlook.com/?url=https://www.earth.li/mailman/listinfo/e3-hacking&data=02%7c01%7c%7cc50113d7016041be38d508d6b86ddbf5%7c84df9e7fe9f640afb435aaaaaaaaaaaa%7c1%7c0%7c636899179308685266&sdata=QJj3kjxdqs0bmwzmyBmEkf4yqTw08XkP8x0gTnxqvtE%3D&reserved=0>
>>>>
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