-
Notifications
You must be signed in to change notification settings - Fork 6
/
cedargrove_nau7802.py
executable file
·337 lines (289 loc) · 12.7 KB
/
cedargrove_nau7802.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
# SPDX-FileCopyrightText: Copyright (c) 2023 JG for Cedar Grove Maker Studios
#
# SPDX-License-Identifier: MIT
"""
`cedargrove_nau7802`
================================================================================
A CircuitPython driver class for the NAU7802 24-bit ADC. Supports dual analog
inputs.
* Author(s): JG
Implementation Notes
--------------------
**Hardware:**
* `NAU7802 FeatherWing; OSH Park project (16-SOIC version)
<https://oshpark.com/shared_projects/qFvEU3Bn>`_
* `NAU7802 FeatherWing; OSH Park project (16-DIP version)
<https://oshpark.com/shared_projects/ZfryHYnc>`_
* `SparkFun Quicc Scale (single channel) <https://www.sparkfun.com/products/15242>`_
* `Adafruit NAU78082 STEMMA QT (single channel) <https://www.adafruit.com/product/4538>`_
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
https://circuitpython.org/downloads
* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
* Adafruit's Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register
"""
import time
import struct
from adafruit_bus_device.i2c_device import I2CDevice
from adafruit_register.i2c_struct import ROUnaryStruct
# from adafruit_register.i2c_struct import UnaryStruct
from adafruit_register.i2c_bits import RWBits
from adafruit_register.i2c_bits import ROBits
from adafruit_register.i2c_bit import RWBit
from adafruit_register.i2c_bit import ROBit
__version__ = "0.0.0+auto.0"
__repo__ = "https://github.com/CedarGroveStudios/CircuitPython_NAU7802.git"
# DEVICE REGISTER MAP
_PU_CTRL = 0x00 # Power-Up Control RW
_CTRL1 = 0x01 # Control 1 RW
_CTRL2 = 0x02 # Control 2 RW
_ADCO_B2 = 0x12 # ADC_OUT[23:16] R-
_ADCO_B1 = 0x13 # ADC_OUT[16: 8] R-
_ADCO_B0 = 0x14 # ADC_OUT[ 7: 0] R-
_OTP_B1 = 0x15 # OTP[15: 8] R-
_ADC = 0x15 # ADC Control -W
_OTP_B0 = 0x16 # OTP[ 7: 0] R-
_PGA = 0x1B # Programmable Gain Amplifier RW
_PWR_CTRL = 0x1C # Power Control RW
_REV_ID = 0x1F # Chip Revision ID R-
# pylint: disable=too-few-public-methods
class LDOVoltage:
"""Internal low-dropout voltage regulator settings."""
LDO_3V0 = 0x5 # LDO 3.0 volts; _CTRL1[5:3] = 5
LDO_2V7 = 0x6 # LDO 2.7 volts; _CTRL1[5:3] = 6
LDO_2V4 = 0x7 # LDO 2.4 volts; _CTRL1[5:3] = 7
class Gain:
"""Analog differential amplifier gain settings."""
GAIN_X1 = 0x0 # Gain X1; _CTRL1[2:0] = 0 (chip default)
GAIN_X2 = 0x1 # Gain X1; _CTRL1[2:0] = 1
GAIN_X4 = 0x2 # Gain X1; _CTRL1[2:0] = 2
GAIN_X8 = 0x3 # Gain X1; _CTRL1[2:0] = 3
GAIN_X16 = 0x4 # Gain X1; _CTRL1[2:0] = 4
GAIN_X32 = 0x5 # Gain X1; _CTRL1[2:0] = 5
GAIN_X64 = 0x6 # Gain X1; _CTRL1[2:0] = 6
GAIN_X128 = 0x7 # Gain X1; _CTRL1[2:0] = 7
class ConversionRate:
"""ADC conversion rate settings."""
RATE_10SPS = 0x0 # 10 samples/sec; _CTRL2[6:4] = 0 (default)
RATE_20SPS = 0x1 # 20 samples/sec; _CTRL2[6:4] = 1
RATE_40SPS = 0x2 # 40 samples/sec; _CTRL2[6:4] = 2
RATE_80SPS = 0x3 # 80 samples/sec; _CTRL2[6:4] = 3
RATE_320SPS = 0x7 # 320 samples/sec; _CTRL2[6:4] = 7
class CalibrationMode:
"""Calibration mode state settings."""
INTERNAL = 0x0 # Offset Calibration Internal; _CTRL2[1:0] = 0 (chip default)
OFFSET = 0x2 # Offset Calibration System; _CTRL2[1:0] = 2
GAIN = 0x3 # Gain Calibration System; _CTRL2[1:0] = 3
class NAU7802:
"""The primary NAU7802 class."""
# pylint: disable=too-many-instance-attributes
def __init__(self, i2c_bus, address=0x2A, active_channels=1):
"""Instantiate NAU7802; LDO 3v0 volts, gain 128, 10 samples per second
conversion rate, disabled ADC chopper clock, low ESR caps, and PGA output
stabilizer cap if in single channel mode."""
self.i2c_device = I2CDevice(i2c_bus, address)
if not self.reset():
raise RuntimeError("NAU7802 device could not be reset")
if not self.enable(True):
raise RuntimeError("NAU7802 device could not be enabled")
self.ldo_voltage = "3V0" # 3.0-volt internal analog power (AVDD)
self._pu_ldo_source = True # Internal analog power (AVDD)
self.gain = 128 # X128
self._c2_conv_rate = ConversionRate.RATE_10SPS # 10SPS default
self._adc_chop_clock = 0x3 # 0x3 = Disable ADC chopper clock
self._pga_ldo_mode = 0x0 # 0x0 = Use low ESR capacitors
self._act_channels = active_channels
# 0x1 = Enable PGA out stabilizer cap for single channel use
self._pc_cap_enable = 0x1
if self._act_channels == 2:
# 0x0 = Disable PGA out stabilizer cap for dual channel use
self._pc_cap_enable = 0x0
self._calib_mode = None # Initialize for later use
self._adc_out = None # Initialize for later use
# DEFINE I2C DEVICE BITS, NYBBLES, BYTES, AND REGISTERS
# Chip Revision R-
_rev_id = ROBits(4, _REV_ID, 0, 1, False)
# Register Reset (RR) RW
_pu_reg_reset = RWBit(_PU_CTRL, 0, 1, False)
# Power-Up Digital Circuit (PUD) RW
_pu_digital = RWBit(_PU_CTRL, 1, 1, False)
# Power-Up Analog Circuit (PUA) RW
_pu_analog = RWBit(_PU_CTRL, 2, 1, False)
# Power-Up Ready Status (PUR) R-
_pu_ready = ROBit(_PU_CTRL, 3, 1, False)
# Power-Up Conversion Cycle Start (CS) RW
_pu_cycle_start = RWBit(_PU_CTRL, 4, 1, False)
# Power-Up Cycle Ready (CR) R-
_pu_cycle_ready = ROBit(_PU_CTRL, 5, 1, False)
# Power-Up AVDD Source (ADDS) RW
_pu_ldo_source = RWBit(_PU_CTRL, 7, 1, False)
# Control_1 Gain (GAINS) RW
_c1_gains = RWBits(3, _CTRL1, 0, 1, False)
# Control_1 LDO Voltage (VLDO) RW
_c1_vldo_volts = RWBits(3, _CTRL1, 3, 1, False)
# Control_2 Calibration Mode (CALMOD) RW
_c2_cal_mode = RWBits(2, _CTRL2, 0, 1, False)
# Control_2 Calibration Start (CALS) RW
_c2_cal_start = RWBit(_CTRL2, 2, 1, False)
# Control_2 Calibration Error (CAL_ERR) RW
_c2_cal_error = RWBit(_CTRL2, 3, 1, False)
# Control_2 Conversion Rate (CRS) RW
_c2_conv_rate = RWBits(3, _CTRL2, 4, 1, False)
# Control_2 Channel Select (CHS) RW
_c2_chan_select = RWBit(_CTRL2, 7, 1, False)
# ADC Result Output MSByte R-
_adc_out_2 = ROUnaryStruct(_ADCO_B2, ">B")
# ADC Result Output MidSByte R-
_adc_out_1 = ROUnaryStruct(_ADCO_B1, ">B")
# ADC Result Output LSByte R-
_adc_out_0 = ROUnaryStruct(_ADCO_B0, ">B")
# ADC Chopper Clock Frequency Select -W
_adc_chop_clock = RWBits(2, _ADC, 4, 1, False)
# PGA Stability/Accuracy Mode (LDOMODE) RW
_pga_ldo_mode = RWBit(_PGA, 6, 1, False)
# Power_Ctrl PGA Capacitor (PGA_CAP_EN) RW
_pc_cap_enable = RWBit(_PWR_CTRL, 7, 1, False)
@property
def chip_revision(self):
"""The chip revision code."""
return self._rev_id
@property
def channel(self):
"""Selected channel number (1 or 2)."""
return self._c2_chan_select + 1
@channel.setter
def channel(self, chan=1):
"""Select the active channel. Valid channel numbers are 1 and 2.
Returns True unless a cycle ready (CR) timeout occurs."""
self.read() # Clear the data buffer
if chan == 1:
self._c2_chan_select = 0x0
elif chan == 2 and self._act_channels == 2:
self._c2_chan_select = 0x1
else:
raise ValueError("Invalid Channel Number")
# Check cycle ready flag; timeout after 1.0 sec
start_check = time.monotonic()
while not self._pu_cycle_ready:
if time.monotonic() - start_check > 1.0:
return False
return True
@property
def ldo_voltage(self):
"""Representation of the LDO voltage value."""
return self._ldo_voltage
@ldo_voltage.setter
def ldo_voltage(self, voltage="EXTERNAL"):
"""Select the LDO Voltage. Valid voltages are '2V4', '2V7', '3V0'."""
if not f"LDO_{voltage}" in dir(LDOVoltage):
raise ValueError("Invalid LDO Voltage")
self._ldo_voltage = voltage
if self._ldo_voltage == "2V4":
self._c1_vldo_volts = LDOVoltage.LDO_2V4
elif self._ldo_voltage == "2V7":
self._c1_vldo_volts = LDOVoltage.LDO_2V7
elif self._ldo_voltage == "3V0":
self._c1_vldo_volts = LDOVoltage.LDO_3V0
@property
def gain(self):
"""The programmable amplifier (PGA) gain factor."""
return self._gain
@gain.setter
def gain(self, factor=1):
"""Select PGA gain factor. Valid values are 1, 2, 4, 8, 16, 32, 64,
and 128."""
if not f"GAIN_X{factor}" in dir(Gain):
raise ValueError("Invalid Gain Factor")
self._gain = factor
if self._gain == 1:
self._c1_gains = Gain.GAIN_X1
elif self._gain == 2:
self._c1_gains = Gain.GAIN_X2
elif self._gain == 4:
self._c1_gains = Gain.GAIN_X4
elif self._gain == 8:
self._c1_gains = Gain.GAIN_X8
elif self._gain == 16:
self._c1_gains = Gain.GAIN_X16
elif self._gain == 32:
self._c1_gains = Gain.GAIN_X32
elif self._gain == 64:
self._c1_gains = Gain.GAIN_X64
elif self._gain == 128:
self._c1_gains = Gain.GAIN_X128
@property
def poll_rate(self):
"""ADC conversion/polling rate."""
return self._c2_conv_rate
@poll_rate.setter
def poll_rate(self, rate=0):
"""Select polling rate. Valid values are 10, 20, 40, 80, and 320."""
if not f"RATE_{rate}SPS" in dir(ConversionRate):
raise ValueError("Invalid Conversion Rate")
self._rate = rate
if self._rate == 10:
self._c2_conv_rate = ConversionRate.RATE_10SPS
if self._rate == 20:
self._c2_conv_rate = ConversionRate.RATE_20SPS
if self._rate == 40:
self._c2_conv_rate = ConversionRate.RATE_40SPS
if self._rate == 80:
self._c2_conv_rate = ConversionRate.RATE_80SPS
if self._rate == 320:
self._c2_conv_rate = ConversionRate.RATE_320SPS
def enable(self, power=True):
"""Enable(start) or disable(stop) the internal analog and digital
systems power. Enable = True; Disable (low power) = False. Returns
True when enabled; False when disabled."""
self._enable = power
if self._enable:
self._pu_analog = True
self._pu_digital = True
time.sleep(0.750) # Wait 750ms; minimum 400ms
self._pu_start = True # Start acquisition system cycling
return self._pu_ready
self._pu_analog = False
self._pu_digital = False
time.sleep(0.010) # Wait 10ms (200us minimum)
return False
def available(self):
"""Read the ADC data-ready status. True when data is available; False when
ADC data is unavailable."""
return self._pu_cycle_ready
def read(self):
"""Reads the 24-bit ADC data. Returns a signed integer value with
24-bit resolution. Assumes that the ADC data-ready bit was checked
to be True."""
adc = self._adc_out_2 << 24 # [31:24] << MSByte
adc = adc | (self._adc_out_1 << 16) # [23:16] << MidSByte
adc = adc | (self._adc_out_0 << 8) # [15: 8] << LSByte
adc = adc.to_bytes(4, "big") # Pack to 4-byte (32-bit) structure
value = struct.unpack(">i", adc)[0] # Unpack as 4-byte signed integer
self._adc_out = value / 128 # Restore to 24-bit signed integer value
return self._adc_out
def reset(self):
"""Resets all device registers and enables digital system power.
Returns the power ready status bit value: True when system is ready;
False when system not ready for use."""
self._pu_reg_reset = True # Reset all registers
time.sleep(0.100) # Wait 100ms; 10ms minimum
self._pu_reg_reset = False
self._pu_digital = True
time.sleep(0.750) # Wait 750ms; 400ms minimum
return self._pu_ready
def calibrate(self, mode="INTERNAL"):
"""Perform the calibration procedure. Valid calibration modes
are 'INTERNAL', 'OFFSET', and 'GAIN'. True if successful."""
if not mode in dir(CalibrationMode):
raise ValueError("Invalid Calibration Mode")
self._calib_mode = mode
if self._calib_mode == "INTERNAL": # Internal PGA offset (zero setting)
self._c2_cal_mode = CalibrationMode.INTERNAL
elif self._calib_mode == "OFFSET": # External PGA offset (zero setting)
self._c2_cal_mode = CalibrationMode.OFFSET
elif self._calib_mode == "GAIN": # External PGA full-scale gain setting
self._c2_cal_mode = CalibrationMode.GAIN
self._c2_cal_start = True
while self._c2_cal_start:
time.sleep(0.010) # 10ms
return not self._c2_cal_error