Documentation for configuring Alchemy HATs for Pi

44 Pages·2016·3.72 MB·English

by  Percy Kawas

1
User Guide for HATs
from Alchemy Power
Inc.
Pi-UpTimeUPS, Pi-UpTimeUPS-BO, Pi-
EzConnect and Pi-16ADC.

1 HATs or Hardware Attached on Top of a Raspberry Pi provides additional capabilities to the Raspberry Pi.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
Contents

Configuring Pi-UpTimeUPS and Pi-16ADC ................................................................................................... 3
Overview ................................................................................................................................................... 3
Pi-EzConnect capabilities ......................................................................................................................... 5
Pi-16ADC capabilities ............................................................................................................................... 7
Pi-UpTimeUPS capabilities ..................................................................................................................... 10
Pi-UpTimeUPS-BO capabilities ............................................................................................................... 12
Connecting Pi-UpTimeUPS and Pi-UpTimeUPS-BO boards ................................................................... 14
LED’s on Pi-UpTimeUPS .......................................................................................................................... 17
Setting up Python ................................................................................................................................... 18
Setting up successive read for I2C .......................................................................................................... 18
Setting up the ADC ports ........................................................................................................................ 19
I2C address .......................................................................................................................................... 20
ADC ports addressing ............................................................................................................................. 21
Python Routines ..................................................................................................................................... 22
rpimonitor .............................................................................................................................................. 23
Setting up the rpimonitor ...................................................................................................................... 23
Installing rpimonitor .............................................................................................................................. 23
Updating rpimonitor .............................................................................................................................. 24
Setting up the auto shutdown ............................................................................................................... 25
APPENDIX A – Python routines .............................................................................................................. 26
Areas of Improvement (enhancements) ............................................................................................... 27
APPENDIX B - Crontab ............................................................................................................................ 28
APPENDIX C - cron-mon+shutdown.py program .................................................................................. 29
APPENDIX D mon+shutdown.py program ............................................................................................. 33
Appendix E – Pi-EzConnect board pin outs ............................................................................................ 37
Frequently Asked Questions (FAQ) ........................................................................................................ 39
Notes: ...................................................................................................................................................... 44

Page | 2 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
Configuring Pi-UpTimeUPS and Pi-16ADC
Revision 1.2
Updated October 2016

Alchemy Power Inc. (API) manufacturers several boards or HATs which are used in conjunction with a
Raspberry Pi. This document provides necessary technical detail on these boards.

The traffic light icon used in the document highlights sections which have to be addressed or
sections where special attention is needed. The Icon is shown here on the left.

Overview
Alchemy Power Inc. designs and manufactures several HAT’s and boards for the Raspberry Pi. All
Raspberry Pi’s with a 40 pin header are supported.
Older Raspberry Pi’s with a 26 pin header are not supported. Please note:
 If you use a Pi-Zero, the boards do work with a Pi-Zero. However, the pin headers for the Pi-Zero
are not installed which can be easily/optionally installed (soldered) by the user.
 The HAT format is defined for a Raspberry Pi, e.g. Raspberry Pi-3. All boards made by Alchemy
Power Inc. follow the HAT recommendation. Raspberry Pi-Zero is a half size board. The boards
designed and sold by Alchemy Power Inc. are full size HAT boards.
A brief overview of the boards designed, manufactured and sold by API is below.
1. Pi-EzConnect - introduced in 2015, this board or HAT allows multiple digital sensors or GPIO to
be securely connected to a Raspberry Pi. Watch the product video at
https://youtu.be/oChXSE0etQw.
2. Pi-16ADC - a sixteen (16) channel or a 16 port Analog to Digital Converter (ADC) board or HAT.
This manual covers details on how the software can be configured and used with the board.
Watch the product video at https://youtu.be/gApMLcfn0A4.
3. Pi-UpTimeUPS - provides Uninterruptible Power Supply2 (or UPS) to the Pi for many hours3. Pi-
UpTimeUPS also allows power mobility. Compact and securely connected, allow you to take the
Pi with you without having to shut-down and reboot it. Software provided monitors battery
level and can shut-down the Pi when battery runs low. Watch the product video at
https://youtu.be/FMIRmrrCF-I.

2 For UPS functionality, two 18650 batteries are needed. These are not provided and have to be purchased and
installed separately.
3 The number of UPS use hours depends on the battery capacity as well as the Raspberry Pi model.
Page | 3 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
4. Pi-UpTimeUPS-BO - combines the functions of Pi-16ADC and Pi-EzConnect in a breakout board
that works with Pi-UpTimeUPS board, with all GPIO ports and twelve analog ports available for
use. 5V UPS and 3.3V UPS power which is generated by Pi-UpTimeUPS board is available for use
on the Pi-UpTimeUPS-BO board. Watch the product video at https://youtu.be/ZMUKscsNk1I.
The instructions covered in this manual are written and tested with a Raspberry Pi-3 Model B board with
the latest operating system.
The ADC chip used on Pi-16ADC as well as the Pi-UpTimeUPS is the Linear Technology LTC 2497 chip.
Data sheet for the chip is recommended for programming the chip for complex uses, e.g. differential
measurements and differential use of the channels. All capabilities of the chip can be used on the
boards.
The Pi-UpTimeUPS board uses the following channels for monitoring the system:
 Channel 15  Used for monitoring input power. Voltage is monitored across the input to ensure
power is on. If the power is on – there is no need to check the battery level. This is monitored by
the hardware on the board.
 Channel 14  Battery Voltage level. The Pi-UpTimeUPS board uses this information to trigger a
shutdown process when the battery power runs low. The battery used is a Lithium-Ion battery.
The power remaining in the batteries can be measured by measuring the voltage level.
Shutdown is triggered when the battery voltage reaches 3.0V.
 Channel 13, 12  for future use.
It is recommended to set the monitoring routine as a cron4 script so that the battery voltage is measured
as often as needed. Minimally, the routine should be run every minute. If the power is not reliable, it
should be run more often via the cron script.
The ADC capabilities for the Pi-UpTimeUPS board are exposed using the Pi-UpTimeUPS-BO board.
Besides the ADC channels, the GPIO channels as well as UPS 3.3V and UPS 5V are also available on Pi-
UpTimeUPS-BO board.
This manual assumes the user is familiar with Linux (Raspbian OS or Pixel or Ubuntu) and is familiar with
command line interface.

4 Cron is a function which allows specific routines to be run routinely at a specific time. It is recommended to run
the routing to monitor power failure as frequently as needed. At a minimum, every five minutes is recommended.
Page | 4 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
Pi-EzConnect capabilities
Capabilities of the Pi-EzConnect board are described below.
 GPIO connections. Provides solder and solderless GPIO connections to all GPIOs on the
Raspberry Pi board. This ensures several sensors or electronics or devices are connected
securely to the board.

 Power connections. Solder and solder free connections are provided for Power and Ground.

Page | 5 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC

 Breadboard. A breadboard area is provided to connect headers for jumper wire connections or
solder electronics.

 Fuse protection. A PTC fuse (installed on the bottom side)protect the 5V and 3.3V connections.

See Appendix E for additional information on connectors and map to GPIO connections.

Page | 6 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
Pi-16ADC capabilities
Capabilities of the Pi-16ADC are described below.
 16-bit resolution. Provides really accurate information (38.1 micro-volt resolution).
 16 analog ports. All ports can be used in different configurations - all set via the software. When
used as a differential pair, up to eight ports is available for use.
 I2C bus. Uses the I2C bus and can coexist with lots of other devices.
 I2C bus address. Have 27 different configurable addresses to pick from. This ensures an easy add to
the I2C bus and virtually guarantees no conflict with other I2C devices.

 Low power consumption. Device drains negligible power if the sensor ports are not used.

Page | 7 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
 Solder and Solderless connections. Easy to connect sensors to Pi-16ADC. The board provides solder-
less connectors. Board also includes solder points for attaching resistors, power for sensors etc.

 Breadboard. A breadboard area is provided to enable electronics or other connections to be
soldered on easily.

Page | 8 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
 Power. Several 5V and ground solder points are available.

 Calibration. No re-calibration needed. ADC chip calibrates itself on power reset.
 Sample Python code. Sample Python code can be used for both Pi-UpTimeUPS as well as Pi-16ADC.
See Appendix A through Appendix D on how the sample Python code can be used.
 Noise Immunity. Immunity to common 50/60 Hz noise.
 LED on/off. Turn the LED off to conserve power.
 HAT. Raspberry Pi HAT form factor - provides compact connections. Pi header pins provide
connections to other HATs.

Intentionally left blank.

Page | 9 ©2016, Alchemy Power Inc. Information can be changed without notice.
User Guide for Pi-UpTimeUPS, Pi-UpTimeUPS-BO,
Pi-EzConnect & Pi-16ADC
Pi-UpTimeUPS capabilities
Install two 18650 batteries in the battery holder in the Pi-UpTimeUPS board. These batteries are
purchased separately and are not included with the Pi-UpTimeUPS board. The 18650 batteries
are available from different manufacturers as well as in different capacities – usually displayed as
mAh or milli-Amp-hours. Purchasing the batteries from a reputable supplier as well as using
reputable technologies is strongly recommended. The Lithium Ion technology today does not
allow for more than 3500 mAh in the 18650 battery format. That could change over time as
technology and chemistry improves. Please make sure a Lithium Ion battery is used. Do not use a
Lithium Phosphate battery. A maximum current of 1.7 Amps is supported by the board.

Pi-UpTimeUPS board provides power mobility to the Raspberry Pi.
PI-UpTimeUPS board provides the following:
 Uninterruptable Power Supply or UPS. The Pi-UptimeUPS board converts the energy stored in
the battery and provides power to the Raspberry Pi.
 Load balancing. Pi-UpTimeUPS board provides power to the attached load as demanded. For
example, if the sensor or any appliance connected to a USB port demands additional power, it
could cause a brown out situation and reboot the Raspberry Pi. With the Pi-UpTimeUPS board,
these demands are addressed by the board and a steady 5V power is provided to the Raspberry
Pi.
 Battery charging. Pi-UpTimeUPS board charges the battery and provides power to the
Raspberry Pi at the same time. This ensures the batteries charge automatically when power is
restored after a power failure.
 3.3V UPS. The Raspberry Pi has an internal power of 3.3V. While the 3.3V is available on pin 1 of
the Raspberry Pi header, it does not have much power capability5 nor is it a very stable power

5 Various articles on the web indicate the 3.3V power is limited to 50mA, of which a significant portion is consumed
by the Raspberry Pi board.
Page | 10 ©2016, Alchemy Power Inc. Information can be changed without notice.