Search found 630 matches

by ag123
Sun Jun 25, 2017 8:43 am
Forum: General discussion
Topic: Should we still use ptimisation level -Os (Small)
Replies: 4
Views: 56

Re: Should we still use ptimisation level -Os (Small)

i'd live with -Os (small) optimizations on maple mini/ blue pill, the -O2 optimizations seem to help in particular on the F4 nevertheless -Os (small) is still preferred for F4 as a default mode i think the main reasons -O2 is faster on F4 are due to 'indiscriminate' optimizations by gcc/g++ (the com...
by ag123
Sun Jun 25, 2017 8:22 am
Forum: General discussion
Topic: SD card on ILI9341 display board??
Replies: 14
Views: 156

Re: SD card on ILI9341 display board??

it do sound like there are various 'versions' of ILI9341 boards floating around, my guess is that the components between different batches of boards are different or even within the same batch it may be different. hence, to be safe, it'd probably be better to be somewhat careful, have a multi-meter ...
by ag123
Sun Jun 25, 2017 8:13 am
Forum: General discussion
Topic: SD card on ILI9341 display board??
Replies: 14
Views: 156

Re: SD card on ILI9341 display board??

on my board for the backlight led pin i initially connected a 220 ohm resistor measure voltages and worked out the on board series resistance. it turns out that the on-board series resistance is 900 ohm in my case http://www.stm32duino.com/viewtopic.php?f=45&t=526&p=27193#p27193 my guess is that if ...
by ag123
Sun Jun 25, 2017 7:58 am
Forum: General discussion
Topic: Combining Blink & Count to the bootloader
Replies: 32
Views: 317

Re: Combining Blink & Count to the bootloader

thus far i'm quite happy with just the 'raw' bootloader, in fact after i installed the bootloader i deliberately zero out blocks of flash after 0x8002000 if i remember correctly, this leaves it in 'perpetual' boot loader mode waiting for sketch install either way the 'perpetual mode' keeps the led b...
by ag123
Sat Jun 24, 2017 7:02 am
Forum: General discussion
Topic: SD card on ILI9341 display board??
Replies: 14
Views: 156

Re: SD card on ILI9341 display board??

for the backlight, i feed a normal gpio pin directly from my maple mini to the backlight pin. http://www.stm32duino.com/viewtopic.php?f=45&t=526&p=27193#p27193 But before you do that, try first with a resistor say a few hundred ohms connecting in series to the backlight pin and measure voltages. i t...
by ag123
Sat Jun 24, 2017 6:10 am
Forum: General discussion
Topic: SD card on ILI9341 display board??
Replies: 14
Views: 156

Re: SD card on ILI9341 display board??

i shorted those series resistors on mine, simply replace them with a single strand of wire each http://www.stm32duino.com/viewtopic.php?f=44&t=2026#p27139 i removed the resistors this way and later solder wires in its place https://www.youtube.com/watch?v=8JM4oCpWnjU it works well for me however, as...
by ag123
Tue Jun 20, 2017 7:15 am
Forum: Projects
Topic: Blue Pill breakout board ?
Replies: 10
Views: 173

Re: Blue Pill breakout board ?

it sounds like a 'shield' but yet isn't exactly a 'shield', i'm thinking perhaps generic perf boards may help? i'm using mainly (baite) maple mini, currently i'm resorting to 'dupont' wires connections, i've been looking for various similar solutions as a lot of those things i use are breakout modul...
by ag123
Thu Jun 15, 2017 8:05 am
Forum: General discussion
Topic: VGA Space invaders on bluepill
Replies: 45
Views: 681

Re: VGA Space invaders on bluepill

Say 400x200pixels, 8bits per pixel (256 colors), 4x 2bit R2R VGA DAC. You need 80kB video buffer, which fits inside F407. You get maybe 50us to shoot out 400pixels or bytes. That is 125ns per pixel. That is an 8MHz byte stream off the gpio. ZX80/81: The ZX81 did not use pixels resolution, but 8x8 f...
by ag123
Wed Jun 14, 2017 12:34 pm
Forum: General discussion
Topic: VGA Space invaders on bluepill
Replies: 45
Views: 681

Re: VGA Space invaders on bluepill

i'm thinking with $2 for each BP/MM it may even be possible to say hook up 2 pieces of it say via spi and one of the bluepill can be dedicated in managing the vga display. so we have a BP/MM running as a 'VGA card' and the other could do dedicated game logic, etc. this would allow 1 BP/MM to use mos...
by ag123
Wed Jun 14, 2017 10:15 am
Forum: General discussion
Topic: VGA Space invaders on bluepill
Replies: 45
Views: 681

Re: VGA Space invaders on bluepill

yup this would fit the '1-bit' colors or rather 8 colors scenario the binary combination of each color signal R, G, B would give 8 color combinations at 3 bits per pixel, 640x480x3/8 ~ 115,200 bytes for the screen buffer my thoughts are that this seem 'easier' on an f407 chip with a good amount of s...