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Forum Index : Microcontroller and PC projects : ASCII Video Terminal
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| WhiteWizzard Guru  Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Just tried composite on my TV/amp combo once again and got nothing (v1.0 on official PCB). VGA works no problem. Will go out now and buy a cheap composite screen and report back later. In the meantime, can you try connecting your USB-to-serial module to pins 5 and 4 (use TeraTerm) AND ALSO connect the ACT LED to pin 14 with a resistor. Disconnect MicroMite - purely have USB module (to TeraTerm) connected directly to Terminal module (pins 4 & 5). Then confirm that LED lights when powered up. If not you have a 'bigger' issue. If LED ok then when you type on keyboard (TeraTerm) then the LED should blink off. We WILL resolve this 
WW |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3282 |
I do not have access to any hardware at this time so I cannot help much but I thoroughly tested composite when I was working on V1.2. I don't know what could behind this issue but composite does work (for me). Geoff Geoff Graham - http://geoffg.net |
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| cosmic frog Guru Joined: 09/02/2012 Location: United KingdomPosts: 302 |
I will be testing v1.2 later tonight. I'll let you all know what happens. Dave. |
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palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1982 |
@WW I have only built the Composite Video circuit. So I only have the 250 and 5 other components. It's one of the simplest things I have ever built and I have checked and rechecked. I will build it up on a proper PCB but don't think that will help. Paul. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Five components? Just need to check something here: Assuming you are using a crystal + 2 caps, and also a 10uF cap (all mentioned in previous post) then this totals four components so far. You then need two resistors on the video output plus ideally a 100nF decoupling cap. This means at least 6 components, or 7 with the decoupling cap. Could your video output be missing a resistor? 150R & 470R are the two values required. PS I could not buy a cheap composite monitor today. I went to a 'hot-spot' in London and the cheapest was £99 for something I can buy on ebay for £23 so will order one online. Let us know about the component count . . . WW |
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| cosmic frog Guru Joined: 09/02/2012 Location: United KingdomPosts: 302 |
HI all, I've just installed v1.2 and it just doesn't work at all, even the led doesn't come on. So I installed v1.0 and everything is back working again, well everything bar the PAL problem. I used a pick it3 programmer to install both firmware. Dave. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1982 |
@WW Yes 8 in all counting the 250. Seems like Cosmic frog has the same problem. Using V1.0 I slowed the micromite baud rate down to 1200 and at least I can see it is trying to print something and scrolling down the screen. I suspect if I could change to NTSC it may be OK. As with Cosmic frog with V1.2 I get nothing. Paul. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3282 |
No, no. V1.2 is an upgrade. You must install it using the bootloader included in the original firmware. You can (and should) install the original firmware using a PIC programmer but after that all upgrades must be done using the bootload facility - which does not require a programmer (just a Windows PC). Full instructions are in the V1.2 upgrade zip file. Geoff Geoff Graham - http://geoffg.net |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
I can confirm that v1.2 works fine with a VGA monitor. I am unable to test composite (PAL and/or NTSC) currently as all my TV's are too new (HDMI only) so I will see if I can borrow a friends old TV to test later. My amp has composite inputs but I can't get any hardware to work on these so inconclusive. As Geoff highlighted, use boot loader to upgrade to v1.2 - his instructions are very clear and easy to follow. WW |
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| cosmic frog Guru Joined: 09/02/2012 Location: United KingdomPosts: 302 |
HI, I will try the update the way Geoff has said. Unfortunately I didn't fit a usb socket to my strip board thinking I could just keep using my pic programmer. Thanks. Dave. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1982 |
I also loaded V1.2 with PicKit3 will try again tomorrow. Paul. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| cosmic frog Guru Joined: 09/02/2012 Location: United KingdomPosts: 302 |
Ok, so I've set up the usb on my board, plugged it in, the led comes on I remove the jumper, the led goes off, so far so good. I run the .exe file and get an error - USB DEVICE WITH VID=0x4D8 and PID=0xFA8D IS NOT FOUND. It's also not listed in the Device Manager, so this tells me the computer is not seeing it. Any ideas? Dave. |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
@Dave, The only way I believe the program won't see the PIC is if there is an open circuit between the PIC and the USB. Ensure D+ and D- from USB are connected to PIC (and correct way round). If you have a spare USB lead it is worth cutting the computer end off to expose the four cables. Then you can check for continuity a lot easier from the green and white wires through to the PIC. I have tested on seven Terminal modules here and all work ok. Two are on official PCB, and 5 are on my variants of my soon-to-be-released TermMite VT100. WW |
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| cosmic frog Guru Joined: 09/02/2012 Location: United KingdomPosts: 302 |
HI WW, I've checked for continuity on all wires and even tried swapping the data wires around but still nothing. I might try a different computer. Thanks. Dave. |
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| cosmic frog Guru Joined: 09/02/2012 Location: United KingdomPosts: 302 |
Just tried another computer, still no joy 
Is there anyway this update could be made to work with a pickit3? Dave. |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
ALL, Finally managed to get a composite signal into a display and can now confirm that PAL and NTSC work on v1.0 AND v1.2.
Only thing now is that the 'editor' wraps across two lines even when using the OPTION LINES xx on the MicroMite. 
The only other thing I can think off regarding anyones composite not working is that some older TVs are based on 50Hz and some 60Hz. I remember reading that some other composite hardware (i.e. DVD players with composite output) working on some TVs and not on others. I don't remember if it was 50Hz that worked or 60Hz that worked - just recollect some people having hassle getting an image. It appears that composite isn't too standard after all!!\ |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6269 |
Have you re flashed with V1 (with the pickit) before trying to do the upgrade? If you have the failed V1.2 on the chip, it will fail because there wont be a bootloader installed. Jim VK7JH MMedit |
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BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
Dave, since 2011 when the Maximites came out, I have had only some of my machines able to work USB to the MM or derivatives. I have had 2 desktop machines in that time and both failed to work with the Maximite. They both had win 7 then various iterations of Win 8. They were both dual booting 32 bit and 64 bit and that made no difference either. Coincidence? they were both ASUS motherboards. I did some diagnostic work and eventually gave up. They would get partly recognised by windows but didn't go all the way to install the device driver. I also tried out several laptops and they worked OK so I had a work around. It was a bit inconvenient but OK. The Micromites were OK because they did not use the MicroChip usb. With the ASCII terminal we are now using the MicroChip usb interface again and several people are reporting that it doesn't work. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1982 |
Looks like it is the end of the line for me, the article stated that you did not have to build the full circuit, all I wanted was a composite display for a project. But it now appears you do have to build the full circuit or you can't upgrade the chip. Paul. @Geoff. would it be too much trouble to bring out a version that can be loaded with a PICKIT3 programmer. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4036 |
What can be done to allow a PICkit3 to be used: edit the hex from the original firmware file - keep the bootloader edit the hext from the upgrade - keep its user data, remove its odd-bootloader and insert the original bootloader then reflash Hex files are just text so it's not hard but is a bit painful. More on hex The bootloader is at (address) 1fc00000 and the hex record for its start looks like :020000041FC01B or :020000041fc01b (because case doesn't matter) Those records have the upper 16 bits of the address. The record type is 04. Lines after such a record are usually data ones (record type 00) so those are the bootloader (until you hit another record 04 and it has another addr see below). Worst case you may have to combine parts of the old and new/odd (if any) bootloader. Probably you can keep all the user area (base addr 1d000000, so type 04 with 1d00). John |
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