Re: custom peripheral registers
- From: cs_posting@xxxxxxxxxxx
- Date: Wed, 13 Jun 2007 17:32:26 -0700
On Jun 13, 5:12 pm, Andrea05 <c...@xxxxxxxx> wrote:
I would like to set a bit of one register from software to tell the
peripheral to start to work. When it has finished, i'd like that the
peripheral sets to ' 0 ' the same bit in order to communicate that the
work is done. In this way setting again the bit to ' 1 ' the
peripheral will start to workagain, and so on.
The problem is: when I syntethize the peripheral I got the error:
Multi-source in Unit <user_logic> on signal <slv_reg3(0)>
Two simple choices:
1) Implement the by by instantiating the vendor's flip flop with
clear. Processor drives data and enable, peripheral drives clear.
2) Describe the desired behaviour of a register: At clock transition
if processor is writing, set to 1. Else if peripheral is done, set to
0. Otherwise, do nothing...
That's assuming you are willing to follow a rule in software of never
writing the bit without first checking to make sure its cleared. And
assuming your peripheral can't clear it until at least a few clocks
after it's been set. And assuming your processor and peripheral share
a clock; if any of these aren't true, it's a little more complicated.
.
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