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from math import ceil
from . import Pmod
from . import MAILBOX_OFFSET
__author__ = "Cathal McCabe, Yun Rock Qu"
__copyright__ = "Copyright 2016, Xilinx"
__email__ = "pynq_support@xilinx.com"
PMOD_TMP2_PROGRAM = "pmod_tmp2.bin"
PMOD_TMP2_LOG_START = MAILBOX_OFFSET+16
PMOD_TMP2_LOG_END = PMOD_TMP2_LOG_START+(1000*4)
RESET = 0x1
READ_SINGLE_VALUE = 0x3
READ_AND_LOG = 0x7
def _reg2float(reg):
"""Translate the register value to a floating-point number.
Note
----
The float precision is specified to be 1 digit after the decimal
point.
Bit [31] (1 bit) -> Sign (S)
Bit [30:23] (8 bits) -> Exponent (E)
Bit [22:0] (23 bits) -> Mantissa (M)
Parameters
----------
reg : int
A 4-byte integer.
Returns
-------
float
The floating-point number translated from the input.
"""
if reg == 0:
return 0.0
sign = (reg & 0x80000000) >> 31 & 0x01
exp = ((reg & 0x7f800000) >> 23) - 127
if exp == 0:
man = (reg & 0x007fffff) / pow(2, 23)
else:
man = 1 + (reg & 0x007fffff) / pow(2, 23)
result = pow(2, exp) * man * ((sign * -2) + 1)
return float("{0:.1f}".format(result))
[docs]class Pmod_TMP2(object):
"""This class controls a temperature sensor Pmod.
The Pmod TMP2 (PB 200-221) is an ambient temperature sensor powered by
ADT7420.
Attributes
----------
microblaze : Pmod
Microblaze processor instance used by this module.
log_interval_ms : int
Time in milliseconds between sampled reads.
"""
def __init__(self, mb_info):
"""Return a new instance of a TMP2 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_TMP2_PROGRAM)
self.log_interval_ms = 1000
[docs] def read(self):
"""Read current temperature value measured by the Pmod TMP2.
Returns
-------
float
The current sensor value.
"""
self.microblaze.write_blocking_command(READ_SINGLE_VALUE)
value = self.microblaze.read_mailbox(0)
return _reg2float(value)
[docs] def set_log_interval_ms(self, log_interval_ms):
"""Set the sampling interval for the Pmod TMP2.
Parameters
----------
log_interval_ms : int
Time in milliseconds between sampled reads of the TMP2 sensor
Returns
-------
None
"""
if log_interval_ms < 0:
raise ValueError("Log length should not be less than 0.")
self.log_interval_ms = log_interval_ms
self.microblaze.write_mailbox(0x4, log_interval_ms)
[docs] def start_log(self):
"""Start recording multiple values in a log.
This method will first call set_log_interval_ms() before writting to
the MMIO.
Returns
-------
None
"""
self.set_log_interval_ms(self.log_interval_ms)
self.microblaze.write_non_blocking_command(READ_AND_LOG)
[docs] def stop_log(self):
"""Stop recording multiple values in a log.
Simply write to the MMIO to stop the log.
Returns
-------
None
"""
self.microblaze.write_non_blocking_command(RESET)
[docs] def get_log(self):
"""Return list of logged samples.
Returns
-------
List of valid samples from the temperature sensor in Celsius.
"""
# First stop logging
self.stop_log()
# Prep iterators and results list
[head_ptr, tail_ptr] = self.microblaze.read_mailbox(0x8, 2)
temps = list()
# Sweep circular buffer for samples
if head_ptr == tail_ptr:
return None
elif head_ptr < tail_ptr:
num_words = int(ceil((tail_ptr - head_ptr) / 4))
data = self.microblaze.read(head_ptr, num_words)
temps += [_reg2float(i) for i in data]
else:
num_words = int(ceil((PMOD_TMP2_LOG_END - head_ptr) / 4))
data = self.microblaze.read(head_ptr, num_words)
temps += [_reg2float(i) for i in data]
num_words = int(ceil((tail_ptr - PMOD_TMP2_LOG_START) / 4))
data = self.microblaze.read(PMOD_TMP2_LOG_START, num_words)
temps += [_reg2float(i) for i in data]
return temps