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Forum Index : Microcontroller and PC projects : VGAMite V5.07.00 alpha releases
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| Volhout Guru  Joined: 05/03/2018 Location: NetherlandsPosts: 3589 |
Not sure that works very well. Yes, the NPN transistors will form some kind of load to the 100 ohm color output, but expect significant color changes result of temperature. Maybe even between top of screen and bottom of screen. Maybe not to bad, since you are trying to mimic a 1980's NTSC color TV. Volhout Edited 2021-11-29 17:54 by Volhout PicomiteVGA PETSCII ROBOTS |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
The code supports the internal RTC. Just add a battery to VBAT and you have a RTC which survives power cuts at almost no current use NB: the pinout is very carefully chosen to maximise pin usage (maximum UART/I2C/PWM/SPI availability) no scope to change |
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Cyber Senior Member  Joined: 13/01/2019 Location: UkrainePosts: 161 |
This is a true argument! Thank you! |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9083 |
@ phil99: Thanks for the schematic.  Smoke makes things work. When the smoke gets out, it stops! |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1995 |
LOL, you're in my mind... My PuTTY sessions all look like this:  @MatherP Think I asked this early on but the design has moved on a bit; will there still be options for a serial console - just on the pins; no USB, monitor, PS2/USB Keyboard + mouse etc. required? Got a couple on the way to play with. I have an immediate interest in this because of the extended MMBasic and the VGA output is a very exciting possibility as a controller with occasional connection (not with KVM on each one or USB connection). If so, this is a very real contender to replace my Mk2s in new designs. Nothing wrong with them but I am on an old version of the firmware (through necessity). h |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
Default is a serial console, you have to enable a PS2 keyboard VGA happens regardless but you don't need to connect a monitor. There is no USB it is just used for a power connector but you could apply power to the 5V pin instead |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1995 |
woot! cheers h |
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Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1595 |
If a microbridge is fitted as suggested (on the motherboard) and a PS2 keyboard is not enabled. Are the pins that would be used for the PS2 keyboard available for normal I/O use? Also would it then be desirable to leave off the PS2 connector? Bill Keep safe. Live long and prosper. |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2294 |
the 1455/microbridge's 'claim to fame' was being able to program the firmware into a pic32, but without this function being of any use here it would be easier to just place a 4-pin TTL serial/power header on the board and connect an external CP2102 based bridge that sits on the back of the USB plug at the PC end. the 1455 solution also draws 10mA, which may be an issue when operating from batteries without any terminal attached. have been looking up USB keyboard host adapters. the only one that really stands out is the one discussed (5 minute video) here: https://www.youtube.com/watch?v=po3FBdY0GS4 another option is a maxim MAX3421E, but to be honest both seem way too much effort and complication to be justified! cheers, rob :-) |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
Yes Connector doesn't matter, pullup resistors should be left off |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
Here are some benchmarks of the VGAMite vs the MM+ @ 100MHz/120MHz for comparison. Remember the VGAMite is running a 640x480 VGA display at the same time as the tests with two separate H/W interrupts each happening 31500 times every second. Both chips are running double precision floating point and neither has H/W support for double precision. Ta tests smaller number is better (heavily weighted to SDcard performance) MM+ @ 100MHz 16257 565035 365102 143456 84823 1174760 VGAMite 8184 315248 255928 120762 65482 766691 Basic speed tests smaller number is better MM+ 120MHz 0.013 0.082 0.135 0.135 0.265 0.380 0.597 0.174 VGAMite 0.013 0.095 0.168 0.166 0.311 0.431 0.637 0.328 Grainbench greater is better MX470/100MHz 2151 grains VGAMite 1944 grains Solar Eclipse smaller is better MM+ @ 100MHz 121.75 seconds VGAMite 115.21 seconds Edited 2021-12-01 02:16 by matherp |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
V5.07.00a2 411VGAV5.07.00a2.zip Minor internal tweaks New command VGA OFF VGA ON does as it says. About a 4% performance improvement with VGA off. Does not free up the three VGA pins - don't ask! |
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thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 3865 |
Not OPTION VGA ON|OFF so as to save a command slot for something more performance critical ? Best wishes, Tom Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
Lots of slots free and no specific bits still to be implemented except a flash command (when I have a board with the chip) |
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| thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 3865 |
Since he has expressed an interest in the VGAmite you could use one of them to add that SWAP command that the Captain is so keen on, it looks like GW-BASIC had it so there is precedent. Best wishes, Tom Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1995 |
good call on SWAP otherwise moving to the marmite (  ) I would be going back to sq1 coz the CSUB wouldn't work - might be a spectacular crash to try tho'Another thing that would be nice is a SPI READ counterpart to SPI WRITE a$. i.e. read LEN(a$) bytes in one go. I have WRITEs paradoxically out-performing READs because of this "omission". also +1 for OPTION VGA ON|OFF for consistency if it counts EDIT: ah! wait - can this be executed in the program code? might be nice to permit sleeping a connected monitor then turning on when activity is detected... ooh, I like that! expecially if you can write to the display while it is off and just have it spring to life when needed. Just like a grown up computer  in which case it might be better to NOT have it as an OPTIONEdited 2021-12-02 01:56 by CaptainBoing |
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| thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 3865 |
The CMM2 has several OPTIONs that a program can change (multiple times) whilst it is running, e.g. OPTION CONSOLE. Best wishes, Tom Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
CSUBs will be available soon so no need for swap. You can write to the display while VGA off. It just turns off the timers that generate the output. SPI READ is available in all MMBasic variants but it reads to an integer array. Not going to special case this as it will just make the VGAMite incompatible |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5771 |
Well, got a new BP and this one showed up in Device Manager as a USB device. It has programmed ok. Tried the original again and that is still completely ignored by Windows. Now to solder the pins on. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8606 |
411VGAV5.07.00a3.zip  CSUB swap 00000000 E9D1B430 E9D02300 E9C04500 E9C12300 BC304500 BF004770 End CSUB Also you can now use the command UPDATE FIRMWARE to put the processor into bootloader mode. I then updated the firmware over the serial console - worked very nicely. This will allow the "boxed" VGAMite to be updated |
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