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flash memory size of the pinguino 220
29-01-2014, 09:44 AM, (This post was last modified: 29-01-2014, 09:59 AM by pingotg.)
#31
RE: flash memory size of the pinguino 220
Really cheap boards (STM32F103C8T6, under US $10 on ebay, free s/h) start with 64KB flash, 20KB RAM and 72MHz (25-30 MIPS).

ST actually make a line of cheap starter kits but choose a bit carefully as they also make Eval boards that are expensive. Cheapest are generally mouser/element14 et al (or ebay sometimes). Look at STM32F4Discovery & STM32F429IDiscovery. They're 1MB or 2MB flash, 192KB/256KB/2MB RAM and 168MHz.

Prices of header-type boards are all over the place - it can be cheaper to get one with more flash & RAM than with less.

There are no fuses or configs to set in a programmer as you can enable/disable blocks at runtime. I/O is memory-mapped so you can DMA to/from memory or peripheral without fuss. Any ARM toolchain will generally be fine partly because of these details. However, if you use floating-point extensively (as you know, people using uC chips tend hardly to do any) you should investigate because Intel/x86 are better than probably any uC (ARM or not).

ST provide example code as source for free.

There are commercial tool vendors but I don't use them as gcc does all I want.

I like boards with JTAG and then use OpenOCD. It can stop, single-step, program, etc and in effect the CPU hardly knows it's happening. ST now use STLink/SWD which is OK but not such a standard and I prefer standards which are vendor-independent so I can move on if the vendor falls behind.

A step up in speed are RPi and Allwinner boards but both are closed in various ways which may or may not bother you. They're slower at GPIO than you'd probably expect but probably fast enough. You'd probably run an OS on them rather than not, and unlikely to be real-time. (You can have various on the ST line if you want but most aren't really big enough for Linux in case you want it.)

HTH,

John
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29-01-2014, 04:46 PM,
#32
RE: flash memory size of the pinguino 220
I have a STM32F4 Discovery. I build my own ARM tool chain and used libopenstm32 (aka libopencm3 nowadays) and ST-LINK/V2 to play with it. This was intended to be the start of the port of Pinguino on ARM but I've never been further than blinking a led Undecided ...
It is easier to complain than it is to do, but it is better to do than it is to complain.
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29-01-2014, 07:06 PM,
#33
RE: flash memory size of the pinguino 220
I suppose there's the Maple project.

John
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31-01-2014, 07:57 PM,
#34
RE: flash memory size of the pinguino 220
Back to the actual subject... having had a play around I'm not sure it's worth rewriting the bootloader to make it smaller. Yes it can be done and it does free up useful space (I hacked a smaller one that part works) but only on PIC32 chips with small flash. That's basically the Olimex MX220 I suspect.

Is it really worth having a limited-feature bootloader just for that board? (I don't know but I'm doubtful.)

John
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31-01-2014, 10:34 PM,
#35
RE: flash memory size of the pinguino 220
(31-01-2014, 07:57 PM)pingotg Wrote: Back to the actual subject... having had a play around I'm not sure it's worth rewriting the bootloader to make it smaller. Yes it can be done and it does free up useful space (I hacked a smaller one that part works) but only on PIC32 chips with small flash. That's basically the Olimex MX220 I suspect.

Is it really worth having a limited-feature bootloader just for that board? (I don't know but I'm doubtful.)

John

Have you tried to compile signal11 free stack with some bootloader code? How big is it at the end? There is no sense in doing it like you said since signall11 stack is already free and available. Writting new stack/bootloader is more about me learning PIC32 hardware, than reeinventing the wheel. But if you already compiled bootloader +signall11, we should sure use it instead of Microchip one while I tinker with this minimalistic version.
Dreaming in Code...
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31-01-2014, 11:07 PM, (This post was last modified: 31-01-2014, 11:08 PM by pingotg.)
#36
RE: flash memory size of the pinguino 220
You can get 2-4KB smaller but what's the point? The fix is a bigger chip than MX220 uses (PIC32MX220F032D) is what I'm suggesting.

Are there any sufficiently good reasons to not use a chip with more flash? 32KB isn't much especially when Microchip crippled it by having only 3KB boot flash - which won't even hold Microchip's own USB bootloader!

It's time to dump crippled chips and for Microchip to join the current century.

John
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31-01-2014, 11:21 PM,
#37
RE: flash memory size of the pinguino 220
(31-01-2014, 11:07 PM)pingotg Wrote: You can get 2-4KB smaller but what's the point? The fix is a bigger chip than MX220 uses (PIC32MX220F032D) is what I'm suggesting.

Are there any sufficiently good reasons to not use a chip with more flash? 32KB isn't much especially when Microchip crippled it by having only 3KB boot flash - which won't even hold Microchip's own USB bootloader!

It's time to dump crippled chips and for Microchip to join the current century.

John

Yep, all true Smile
Dreaming in Code...
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01-02-2014, 12:49 PM, (This post was last modified: 01-02-2014, 12:49 PM by pingotg.)
#38
RE: flash memory size of the pinguino 220
However... the idea of moving from Microchip's USB code to an open source one (I guess signal11) looks good. The Mcrochip one's encumbered and seems buggy plus hard to read so another one is an attractive idea.

Particularly for the run-time (user) apps. Whether it also ends up in the bootloader... not urgent, as I see it.

John
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