NAME RPi::ADC::ADS - Interface to ADS 1xxx series analog to digital converters (ADC) on Raspberry Pi SYNOPSIS use RPi::ADC::ADS; my $adc = RPi::ADC::ADS->new; # voltage level my $volts = $apc->volts; # percent of input capacity my $percent = $apc->percent; # raw input value my $integer = $apc->raw; DESCRIPTION Perl interface to the Adafruit ADS 1xxx series Analog to Digital Converters (ADC) on the Raspberry Pi. Provides access via the i2c bus to all four input channels on each ADC, while performing correct bit-shifting between the 12-bit and 16-bit resolution on the differing models. PHYSICAL SETUP List of pinouts between the ADC and the Raspberry Pi. ADC Pi ----------- VDD Vcc GND Gnd SCL SCL (NOT SCLK) SDA SDA ADDR Gnd (see below for more info) ALRT NC (no connect) Pinouts `A0' through `A3' on the ADC are the analog pins used to connect to external peripherals (specified in this software as `0' through `3'). The `ADDR' pin specifies the memory address of the ADC unit. Four ADCs can be connected to the i2c bus at any one time. By default, this software uses address `0x48', which is the address when the `ADDR' pin is connected to `Gnd' on the Raspberry Pi. Here are the addresses for the four Pi pins: Pin Address --------------- Gnd 0x48 VDD 0x49 SDA 0x4A SCL 0x4B METHODS new Parameters: model Optional. The model number of the ADC. If not specified, we use `ADS1015'. Models that start with `ADS11' have 16-bit accuracy resolution, and models that start with `ADS10' have 12-bit resolution. addr Optional. The hex location of the ADC. If the pinout in PHYSICAL SETUP is used, this will be `0x48' (which is the default if not supplied). device Optional. The filesystem path to the i2c device file. Defaults to `/dev/i2c-1' channel Optional. One of `0' through `A3' which specifies which channel to read. If not sent in, we default to `0' throughout the object's lifecycle. volts($channel) Retrieves the voltage level of the channel. Parameters: $channel Optional: String, `0' through `3', representing the ADC input channel to read from. Setting this parameter allows you to read all four channels without changing the default set in the object. Return: A floating point number between `0' and the maximum voltage output by the Pi's GPIO pins. percent($channel) Retrieves the ADC channel's input value by percentage of maximum input. Parameters: See `$channel' in volts. raw($channel) Retrieves the raw value of the ADC channel's input value. Parameters: See `$channel' in volts. addr($hex) Sets/gets the ADC memory address. After object instantiation, this method should only be used to get (ie. don't send in any parameters. Parameters: $hex Optional: A memory address in the form `0xNN'. channel($mux) Sets/gets the currently registered ADC input channel within the object. Parameters: $mux Optional: String, `0' through `3', representing the ADC's multiplexer input channel to read from. register($binary) Sets/gets the ADC's registers. This has been left public for convenience for those who understand the hardware very well. It really shouldn't be used otherwise. Parameters: $binary Optional: A binary string (literal 1s and 0s), 32 bits long. TECHNICAL DATA REGISTERS The write buffer consists of an array with three elements. Element `0' selects the register to use. `0' for the conversion register and `1' for the configuration register. Element `1' is a byte long, and represents bits 15-8 of a register, while element `2' represents bits 7-0. CONFIG REGISTER Bit 15 should always be set to `1' when writing. This initiates a conversation ADC. When reading, this bit will read `1' if a conversion is currently occuring, and `0' if the current conversion is complete. Bits 14-12 represent the ADC input channel, as well as either a single-ended (difference between HIGH and GRD) or differential mode (difference between two input channels). Only single-ended is currently supported. Below is the binary representation for the input channels (bits 14-12): Input Binary A0 100 A1 101 A2 110 A3 111 Bits 11-9 are for the programmable gain amplifier. This software uses `001' or 4.096V to cover the Pi's 3.3V output. 000: FS = ±6.144V(1) 100: FS = ±0.512V 001: FS = ±4.096V(1) 101: FS = ±0.256V 010: FS = ±2.048V (hw default) 110: FS = ±0.256V 011: FS = ±2.024V 111: FS = ±0.256V Bit 8 is for the conversion operation mode. We use single conversion hardware default. 0: continuous conversion 1: single conversion (hw default) Bits 9-5 represent the data rate. We use 128SPS: 000 : 128SPS 100 : 1600SPS (hw default) 001 : 250SPS 101 : 2400SPS 010 : 490SPS 110 : 3300SPS 011 : 920SPS 111 : 3300SPS Bit 4 is unused. Bit 3 is the comparator polarity. We use Active Low by default: 0 - Active Low (hw default) 1 - Active High Bit 2 is unused. Bits 1-0 represent the comparator queue. This software has disabled it: 00 : Assert after one conversion 01 : Assert after two conversions 10 : Assert after four conversions 11 : Disable comparator (default) See the https://cdn-shop.adafruit.com/datasheets/ads1015.pdf for further information. SEE ALSO WiringPi::API, RPi::WiringPi, RPi::DHT11 AUTHOR Steve Bertrand, COPYRIGHT AND LICENSE Copyright (C) 2017 by Steve Bertrand This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.22.2 or, at your option, any later version of Perl 5 you may have available.