Source code for pynq.lib.pmod.pmod_tc1

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from struct import pack
from struct import unpack
from math import ceil
from . import Pmod
from . import MAILBOX_OFFSET


__author__ = "Thomas Fors"
__copyright__ = "Copyright 2016, Xilinx"
__email__ = "pynq_support@xilinx.com"


PMOD_TC1_PROGRAM = "pmod_tc1.bin"
PMOD_TC1_LOG_START = MAILBOX_OFFSET+16
PMOD_TC1_LOG_END = PMOD_TC1_LOG_START+(1000*4)
RESET = 0x1
READ_SINGLE_VALUE = 0x3
READ_AND_LOG = 0x7


[docs]def reg_to_tc(reg_val): """Extracts Thermocouple temperature from 32-bit register value. Parameters ---------- reg_val : int 32-bit TC1 register value Returns ------- float The thermocouple temperature in degC. """ v = reg_val >> 18 if v & 0x00020000: v |= 0xfffc0000 else: v &= 0x0003ffff v = unpack('<i', pack('<I', v))[0] return v * 0.25
[docs]def reg_to_ref(reg_val): """Extracts Ref Junction temperature from 32-bit register value. Parameters ---------- reg_val : int 32-bit TC1 register value Returns ------- float The reference junction temperature in degC. """ v = reg_val >> 4 if v & 0x00000800: v |= 0xfffff000 else: v &= 0x00000fff v = unpack('<i', pack('<I', v))[0] return v * 0.0625
[docs]def reg_to_alarms(reg_val): """Extracts Alarm flags from 32-bit register value. Parameters ---------- reg_val : int 32-bit TC1 register value Returns ------- u32 The alarm flags from the TC1. bit 0 = 1 if thermocouple connection is open-circuit; bit 1 = 1 if thermocouple connection is shorted to generated; bit 2 = 1 if thermocouple connection is shorted to VCC; bit 16 = 1 if any if bits 0-2 are 1. """ return reg_val & 0x0001000f
[docs]class Pmod_TC1(object): """This class controls a thermocouple Pmod. The Digilent PmodTC1 is a cold-junction thermocouple-to-digital converter module designed for a classic K-Type thermocouple wire. With Maxim Integrated's MAX31855, this module reports the measured temperature in 14-bits with 0.25 degC resolution. 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 TC1 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_TC1_PROGRAM) self.log_interval_ms = 1000
[docs] def read_raw(self): """Read full 32-bit register of TC1 Pmod. Returns ------- int The current register contents. """ self.microblaze.write_blocking_command(READ_SINGLE_VALUE) return self.microblaze.read_mailbox(0)
[docs] def read_junction_temperature(self): """Read the reference junction temperature. Returns ------- float The reference junction temperature in degC. """ return reg_to_ref(self.read_raw())
[docs] def read_thermocouple_temperature(self): """Read the reference junction temperature. Returns ------- float The thermocouple temperature in degC. """ return reg_to_tc(self.read_raw())
[docs] def read_alarm_flags(self): """Read the alarm flags from the raw value. Returns ------- u32 The alarm flags from the TC1. bit 0 = 1 if thermocouple connection is open-circuit; bit 1 = 1 if thermocouple connection is shorted to generated; bit 2 = 1 if thermocouple connection is shorted to VCC; bit 16 = 1 if any if bits 0-2 are 1. """ return reg_to_alarms(self.read_raw())
[docs] def set_log_interval_ms(self, log_interval_ms): """Set the length of the log in the TC1 Pmod. This method can set the length of the log, so that users can read out multiple values in a single log. Parameters ---------- log_interval_ms : int The length of the log in milliseconds, for debug only. 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. Note ---- The logged samples are raw 32-bit samples captured from the sensor. Returns ------- list List of valid samples from the TC1 sensor """ # Stop logging self.stop_log() # Prep iterators and results list [head_ptr, tail_ptr] = self.microblaze.read_mailbox(0x8, 2) readings = [] # 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) readings += data else: num_words = int(ceil((PMOD_TC1_LOG_END - head_ptr) / 4)) data = self.microblaze.read(head_ptr, num_words) readings += data num_words = int(ceil((tail_ptr - PMOD_TC1_LOG_START) / 4)) data = self.microblaze.read(PMOD_TC1_LOG_START, num_words) readings += data return readings