Building (and testing) the Cheap and Tiny FPGA board.

RE: Building (and testing) the Cheap and Tiny FPGA board.

DAB — Mon, 31 Dec 2018 22:10:00 GMT

Very good post.

Great detective work in finding a good option.

DAB

RE: Building (and testing) the Cheap and Tiny FPGA board.

shabaz — Mon, 31 Dec 2018 20:06:23 GMT

Hi Michael,

It looks like a fun board : )

I'm not too great on macros, (kind of used to quickly closing any header file, if I cant see it then it doesn't exist : )

so a guess is something to do with needing to split the comma during a first pass, but maybe the GPIO0 define is preventing that unless it is done in a second macro?

I tried this on my PC, since curiosity got the better of me..

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=%23include+%3Cstdio.h%3E%0A%0A%23define+LED+GPIO0%2C4%0A%2F%2F+comment+out+the+two+macros+for+now%0A%2F%2F%23define+GPIO%28g%2C+p%29+GPIO_%28g%2C+p%29%0A%2F%2F%23define+GPIO_%28g%2C+p%29+g%0A%0A%2F%2F%23define+PIN%28g%2C+p%29+PIN_%28g%2C+p%29%0A%2F%2F%23define+PIN_%28g%2C+p%29+p%0A%0A%2F%2F+try+just+single+macros%3A%0A%23define+GPIO%28g%2C+p%29+g%0A%23define+PIN%28g%2C+p%29+p%0A%0A%0A%23define+GPIO0++++%28%28mxc_gpio_regs_t*%29MXC_BASE_GPIO0%29%0A%0A%0A%23define+PIN_SET%28p%29+%28GPIO%28p%29-%3Eout_set+%3D+1+%3C%3C+PIN%28p%29%29%0A%23define+PIN_CLR%28p%29+%28GPIO%28p%29-%3Eout_clr+%3D+1+%3C%3C+PIN%28p%29%29%0A%0Atypedef+struct+bob%0A%7B%0A++char+out_set%3B%0A++char+out_clr%3B%0A%7D+mxc_gpio_regs_t%3B%0A%0A%0Amxc_gpio_regs_t+reg%3B%0Amxc_gpio_regs_t*+MXC_BASE_GPIO0%3B%0A%0Aint%0Amain%28void%29%0A%7B%0A++MXC_BASE_GPIO0%3D%26reg%3B%0A++MXC_BASE_GPIO0-%3Eout_set%3D0%3B++%2F%2F+set+to+some+initial+value%0A++MXC_BASE_GPIO0-%3Eout_clr%3D0%3B%0A%0A++PIN_SET%28LED%29%3B++%2F%2F+try+it+out%21%0A%0A++printf%28%22out_set+is+0x%25x%5Cn%22%2C++MXC_BASE_GPIO0-%3Eout_set%29%3B%0A%0A%0A++return%280%29%3B%0A%7D]

For me, the single macro seems to give the right result, it prints out_set is 0x10) but this is with gcc on x86.

RE: Building (and testing) the Cheap and Tiny FPGA board.

genebren — Mon, 31 Dec 2018 16:24:19 GMT

Very nice update on this tiny board. Almost twelve years ago I ran into the exact same problem on my first attempt using ARM based microprocessors. After many experiments I was able to get up to the magical 8MHz toggle rate using a peripheral clock rate of 48MHz. I was shocked and dismayed with such a low rate, as I had designed a whole system around the concept of getting much faster clocking. Oh well, at least you have an FPGA ready to handle faster clocks.

Gene

RE: Building (and testing) the Cheap and Tiny FPGA board.

Jan Cumps — Mon, 31 Dec 2018 16:18:59 GMT

I’m trying to break the macro riddle, to see why it is multi step. On paper because I’m away from compilers until Sunday.

An idea for a breakout board that’s FPGA-interesting? 2 DACs, so you can build a dsp that takes digitised sound in and then manipulates the signals?