#garfield Logs

May 12 2021

12:24 AM rue_bed: I never seem to get the cores returned
11:33 AM rue_mohr: so, I wonder
11:33 AM rue_mohr: I wonder how well an stm32 can drive an old monochrome screen
03:16 PM rue_mohr: wow, I came up with a VCO, and it goes from 1Hz to 97kHz
03:17 PM rue_mohr: and it does the 1Hz with a 0.01uF timing cap!!!
05:48 PM polprog: I had an STM32, or an atmega (or both) generate a 15kHz video signal pretty swiftly
05:48 PM polprog: a bit of timer and spi magic and you can have a bitmapped display
06:14 PM rue_mohr: composite? vga?
06:36 PM polprog: composite
06:36 PM polprog: a couple resistors on gpio to generate white, black and blank levels and youre good to go
06:37 PM polprog: with a SPI output you can send serial data fast enough to be a pixel clock for a 100 or so px per line
06:37 PM polprog: i want to make a doodad that syncs to existing video signal and renders an overlay on it in a similar way
06:37 PM polprog: id just need a sync detector that would trigger the micro
06:42 PM rue_mohr: lots of sync detector circuits out there
06:42 PM rue_mohr: and chips
06:42 PM rue_mohr: you have some I think in that batc
06:42 PM rue_mohr: h
06:42 PM rue_mohr: the deflection controller
06:42 PM rue_mohr: should have a composite input and two sync outputs
06:51 PM rue_mohr: polprog, do you have a source for those clips?
06:53 PM polprog: sure
06:55 PM polprog: https://www.aliexpress.com/item/1005001780985115.html
06:55 PM rue_mohr: hey polprog
06:55 PM rue_mohr: if your reading data from an SD card, serial
06:55 PM polprog: hey rue_mohr
06:55 PM rue_mohr: will it just read every byte on the card and then loop?
06:55 PM polprog: hmm
06:56 PM polprog: no idea.. probably faster to check experimentally
06:56 PM rue_mohr: an i2c chip will
06:56 PM rue_mohr: I have a 256k serial ram chip
06:56 PM polprog: gonna make a video card with it
06:57 PM rue_mohr: which isn't enough for 640x480
06:57 PM rue_mohr: I suppose it cant be i2c, the handshaking would screw up the stream
06:58 PM rue_mohr: how much ram does the stm32 have
06:59 PM polprog: f103 has 20k of ram and 64 /128k of flash
06:59 PM rue_mohr: min 6k bytes
06:59 PM rue_mohr: oh
07:00 PM rue_mohr: I think its 10k
07:00 PM rue_mohr: hmm
07:03 PM rue_mohr: 460x480 is 38kbytes
07:03 PM rue_mohr: er, 640*480
07:04 PM rue_mohr: 320*200 is 8kbytes
07:33 PM Tom_L: ironic they release a 2020 coin with a bat on the back: https://catalog.usmint.gov/national-park-of-american-samoa-2020-rolls-and-bags-MASTER_SAMOA.html?cgid=2020-product-schedule
07:34 PM rue_mohr: no I think that things just get slipped thru by clever people
07:36 PM polprog: heh
08:02 PM rue_mohr: like that AI phone app add where 2 of the 3 demos clearly show it failing to do what its said to