ZPU address

[yosel.b...@gmail.com]

Hi every one. I am new with the ZPU soft processor, but i'm making a little design that uses a 32 bit GPIO and UART i am trying to locate the GPIO at 0x1000 address and the UART at 0x1003. The problem is that only the GPIO works fine, i try changing the address and i can see that both GPIO and UART works at 0x800, 0x1000, 0x2000 and any address with only one bit high. I am using a "case" statement to compare the whole address port and this is implemented in a cyclone II FPGA. Any one can help me please.       

[Lange, Bert]

Hi!

I see two points:

1. Addresses are usually count bytewise, but in a 32 bit system a memory location
contain 4 bytes, consecutive addresses are increased by 4.
I would set the UART to 0x00001004, 0x00001008, 0x0000100c or something like that.

2. Your address decoding is incomplete, so you get the same effect like
on 8 bit home computers (these times the address decoders where expensive): Your devices are shown
several times in the memory map.
If your case statement does really compares all 32 address bits, than there might be another place in the ZPU which
does incomplete address decoding.
To explore such things I use a simulator like ghdl/gtkwave or modelsim.

regards,
Bert

[yosel.b...@gmail.com]

Ok thanks you.