BREWCOP is a Raspberry pi that Electronically Weighs COffee Pots
A 2018 Hackathon project produced an early version of this python script, which talks to a point-of-sale scale sitting under the Technivorm Moccamaster at work. Slack notifications are issued when the pot transitions to brewing, ready, or empty. The scale is also functional for weighing beans.
The Raspberry Pi 2 used in this project has a Touch Screen.
It uses the Pi DSI connector for data, and the Pi GPIO for power:
- Pin 4 (5V) to red wire
- Pin 6 (GND) to black wire
The pi is configured to login as brewcop automatically and start
brewcop.py which takes over the display using urwid.
Urwood needs to be installed:
sudo apt install python3-urwid
The scale is a Avery-Berkel 6702 bench scale purchased on Ebay.
It is interfaced to the Pi via a serial port. Since the scale runs at standard RS-232 signal levels and the Pi serial port uses 3V3 signaling, a NulSom Inc. Ultra Compact RS232 to TTL Converter with Male DB9 (3.3V to 5V) is built into the DB-9 connector shell. The converter connects to the Pi GPIO:
- Pin 1 (3V3) to red wire
- Pin 9 (GND) to black wire
- Pin 8 (UART TX) to brown wire
- Pin 10 (UART RX) to orange wire
The device appears as /dev/ttyAMA0 on the Pi, after disabling
console output in raspi-config. No NULL modem adapter was
required between the converter and the scale, which expects a
serial configuration of 9600,7N1.
The query program down in the test directory can be used to do a
quick weight query to the scale to test connectivity.
$ ./query
0.000000
The Pi 2 doesn't have on-board wifi, so a WiPi USB network dongle is used.
The hostname is brewcop.local.
When configuring the brewcop "app" in Slack, select "Incoming Webhooks",
enable them, and select the channel in your workspace that brewcop should
post in. Ensure that SLACK_WEBHOOK_URL is set to the URL shown in the
environment of brewcop.py.
SPDX-License-Identifier: LGPL-3.0
LLNL-CODE-764420