Skip to content

applet.interface.freq_counter: implement basic frequency counter #218

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
attie wants to merge 13 commits into
base: main
Choose a base branch
from
Draft

applet.interface.freq_counter: implement basic frequency counter #218

Changes from 1 commit
Commits
Show all changes
13 commits
Select commit Hold shift + click to select a range
ab96494
platform.ice40: add support for getting an async-safe ripple counter …
attie-argentum Oct 18, 2020
e57b398
gateware.ripple: add support for a ripple counter, with external clock
attie-argentum Oct 18, 2020
a098c73
support.si_prefix: implement "real" to "scaled with si prefix" number…
attie-argentum Oct 11, 2020
95f2e25
WIP: applet.interface.freq_counter: implement basic frequency counter
attie-argentum Oct 18, 2020
09aec7b
WIP: add --duration argument
attie-argentum Dec 30, 2020
8d8f40e
WIP: move control into FrequencyCounterInterface()
attie-argentum Dec 30, 2020
c9cc042
WIP: fixup num_to_si() ... 1 Hz in should give 1 Hz out, not 1000 mHz
attie-argentum Dec 30, 2020
de13266
WIP: add precision to output report
attie-argentum Dec 30, 2020
26e8351
WIP: add note about slow edges
attie-argentum Dec 30, 2020
3f69395
WIP: add pull-downs
attie-argentum Dec 30, 2020
1a6bbbf
WIP: add interact() phase, so that interaction can be scripted
attie-argentum Dec 30, 2020
5646fc4
WIP: reduce to 32-bit again... 64-bit registers aren't "atomic"
attie-argentum Dec 30, 2020
e0155fd
WIP: add note about runtime vs max freq
attie-argentum Dec 30, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 11 additions & 8 deletions software/glasgow/applet/interface/freq_counter/__init__.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,7 @@ def elaborate(self, platform):
rst=trigger,
clk=self.pads.i_t.i,
clk_en=self.running,
width=64,
width=32,
Copy link
Member

@whitequark whitequark Jun 1, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The gateware doesn't care about the register width at all, a 1-bit one is as atomic as a 128-bit. The reads are always atomic. The writes are never atomic, they are shifted in in 8-bit chunks. (This is probably a bug.)

)
m.d.comb += self.edge_count.eq(m.submodules.ripple.count)

Expand All @@ -63,7 +63,7 @@ async def configure(self, duration=2.0):
ctr = int(self.applet.sys_clk_freq * duration)

# this is broken (see comment below)
#await self.device.write_register(self.applet.__reg_clk_count, ctr, width=8)
#await self.device.write_register(self.applet.__reg_clk_count, ctr, width=4)

await self.applet.set_clk_count(ctr)

Expand Down Expand Up @@ -115,8 +115,8 @@ def add_build_arguments(cls, parser, access):
def build(self, target, args):
self.mux_interface = iface = target.multiplexer.claim_interface(self, args)

reg_clk_count, self.__reg_clk_count = target.registers.add_rw(64)
reg_edge_count, self.__reg_edge_count = target.registers.add_ro(64)
reg_clk_count, self.__reg_clk_count = target.registers.add_rw(32)
reg_edge_count, self.__reg_edge_count = target.registers.add_ro(32)
reg_running, self.__reg_running = target.registers.add_ro(1)

subtarget = iface.add_subtarget(FrequencyCounterSubtarget(
Expand Down Expand Up @@ -174,16 +174,19 @@ async def interact(self, device, args, freq_ctr):
# File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/interface/freq_counter/__init__.py", line 85, in measure
# await self.configure(duration)
# File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/interface/freq_counter/__init__.py", line 60, in configure
# await self.device.write_register(self.applet.__reg_clk_count, ctr, width=8)
# await self.device.write_register(self.applet.__reg_clk_count, ctr, width=4)
# AttributeError: 'FrequencyCounterApplet' object has no attribute '_FrequencyCounterInterface__reg_clk_count'

async def get_clk_count(self):
return await self.device.read_register(self.__reg_clk_count, width=8)
return await self.device.read_register(self.__reg_clk_count, width=4)
async def set_clk_count(self, value):
await self.device.write_register(self.__reg_clk_count, value, width=8)
await self.device.write_register(self.__reg_clk_count, value, width=4)

async def get_ctr(self):
return await self.device.read_register(self.__reg_ctr, width=4)

async def get_edge_count(self):
return await self.device.read_register(self.__reg_edge_count, width=8)
return await self.device.read_register(self.__reg_edge_count, width=4)

async def get_running(self):
return bool(await self.device.read_register(self.__reg_running, width=1))