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from . import Pmod
__author__ = "Cathal McCabe, Yun Rock Qu"
__copyright__ = "Copyright 2016, Xilinx"
__email__ = "pynq_support@xilinx.com"
PMOD_DPOT_PROGRAM = "pmod_dpot.bin"
CANCEL = 0x1
SET_POT_SIMPLE = 0x3
SET_POT_RAMP = 0x5
[docs]class Pmod_DPOT(object):
"""This class controls a digital potentiometer Pmod.
The Pmod DPOT (PB 200-239) is a digital potentiometer powered by the
AD5160. Users may set a desired resistance between 60 ~ 10k ohms.
Attributes
----------
microblaze : Pmod
Microblaze processor instance used by this module.
"""
def __init__(self, mb_info):
"""Return a new instance of a DPOT object.
Parameters
----------
mb_info : dict
A dictionary storing Microblaze information, such as the
IP name and the reset name.
"""
self.microblaze = Pmod(mb_info, PMOD_DPOT_PROGRAM)
[docs] def write(self, val, step=0, log_ms=0):
"""Write the value into the DPOT.
This method will write the parameters "value", "step", and "log_ms"
all together into the DPOT Pmod. The parameter "log_ms" is only used
for debug; users can ignore this parameter.
Parameters
----------
val : int
The initial value to start, in [0, 255].
step : int
The number of steps when ramping up to the final value.
log_ms : int
The length of the log in milliseconds, for debug only.
Returns
-------
None
"""
if not 0 <= val <= 255:
raise ValueError("Initial value should be in range [0, 255].")
if not 0 <= step <= (255-val):
raise ValueError("Ramp steps should be in range [0, {}]."
.format(255-val))
if log_ms < 0:
raise ValueError("Requested log_ms value cannot be less than 0.")
self.microblaze.write_non_blocking_command(CANCEL)
self.microblaze.write_mailbox(0, [val, step, log_ms])
if step == 0:
self.microblaze.write_non_blocking_command(SET_POT_SIMPLE)
else:
self.microblaze.write_non_blocking_command(SET_POT_RAMP)