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base repository: whitequark/glasgow
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head repository: whitequark/glasgow
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compare: c285dfa943ab
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  • 3 commits
  • 2 files changed
  • 1 contributor

Commits on Mar 1, 2019

  1. access.direct.demultiplexer: support pulls in claim_interface(). 

    This has to be done specifically in claim_interface because it needs
to be correctly sequenced with relation to IO voltage changes. This
is not ideal, but works as a first approximation, and it is not clear
what a significantly better solution would be.
    @whitequark
    whitequark committed Mar 1, 2019
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    865ffc4 View commit details

  2. access.direct.demultiplexer: warn on use of pulls with revC0.

    @whitequark
    whitequark committed Mar 1, 2019
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    19839c6 View commit details

  3. applet.i2c_master: add --pulls option, to enable pullups on SCL/SDA.

    @whitequark
    whitequark committed Mar 1, 2019
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    c285dfa View commit details
Showing with 50 additions and 2 deletions.
  1. +37 −1 software/glasgow/access/direct/demultiplexer.py
  2. +13 −1 software/glasgow/applet/i2c_master/__init__.py
38 changes: 37 additions & 1 deletion software/glasgow/access/direct/demultiplexer.py
View file
Original file line number Diff line number Diff line change
@@ -36,7 +36,7 @@ def __init__(self, device):
super().__init__(device)
self._claimed = set()

async def claim_interface(self, applet, mux_interface, args):
async def claim_interface(self, applet, mux_interface, args, pull_low=set(), pull_high=set()):
assert mux_interface._pipe_num not in self._claimed
self._claimed.add(mux_interface._pipe_num)

@@ -55,6 +55,42 @@ async def claim_interface(self, applet, mux_interface, args):
elif hasattr(args, "keep_voltage") and args.keep_voltage:
applet.logger.info("port voltage unchanged")

if self.device.has_pulls:
if self.device.revision == "C0":
if pull_low or pull_high:
applet.logger.error("Glasgow revC0 has severe restrictions on use of configurable "
"pull resistors; device may require power cycling")
await self.device.set_pulls(args.port_spec, pull_low, pull_high)
else:
# Don't touch the pulls; they're either in the power-on reset high-Z state, or
# they have been touched by the user, and we've warned about that above.
pass

else:
await self.device.set_pulls(args.port_spec, pull_low, pull_high)
if pull_low or pull_high:
applet.logger.info("port(s) %s pull resistors configured",
", ".join(sorted(args.port_spec)))
else:
applet.logger.debug("port(s) %s pull resistors disabled",
", ".join(sorted(args.port_spec)))

elif pull_low or pull_high:
# Some applets request pull resistors for bidirectional pins (e.g. I2C). Such applets
# cannot work on revA/B because of the level shifters and the applet should require
# an appropriate revision.
# Some applets, though, request pull resistors for unidirectional, DUT-controlled pins
# (e.g. NAND flash). Such applets can still work on revA/B with appropriate external
# pull resistors, so we spend some additional effort to allow for that.
if pull_low:
applet.logger.warn("port(s) %s requires external pull-down resistors on pins %s",
", ".join(sorted(args.port_spec)),
", ".join(map(str, pull_low)))
if pull_high:
applet.logger.warn("port(s) %s requires external pull-up resistors on pins %s",
", ".join(sorted(args.port_spec)),
", ".join(map(str, pull_high)))

await iface.reset()
return iface

14 changes: 13 additions & 1 deletion software/glasgow/applet/i2c_master/__init__.py
View file
Original file line number Diff line number Diff line change
@@ -266,8 +266,20 @@ def build(self, target, args):
period_cyc=math.ceil(target.sys_clk_freq / (args.bit_rate * 1000))
))

@classmethod
def add_run_arguments(cls, parser, access):
super().add_run_arguments(parser, access)

parser.add_argument(
"--pulls", default=False, action="store_true",
help="enable integrated pull-ups")

async def run(self, device, args):
iface = await device.demultiplexer.claim_interface(self, self.mux_interface, args)
pulls = set()
if args.pulls:
pulls = {args.pin_scl, args.pin_sda}
iface = await device.demultiplexer.claim_interface(self, self.mux_interface, args,
pull_high=pulls)
i2c_iface = I2CMasterInterface(iface, self.logger)
return i2c_iface