Column: Electronics design
Setting up a Flowcode App Developer data logger
W
By Martin Whitlock, Applications Engineer, Matrix TSL
ith Flowcode’s App Developer it is very easy to create and store fi les on your local
hard drive. With in-built components such as the CSV writer, a fi le can easily be created and loaded into Excel for chart plotting and further analysis. With a Flowcode array of open-source API components, data can be pulled from real-world electronic hardware, such as a USB-connected Arduino Uno or a WiFi- connected ESP32, for example. We can use Flowcode’s basic analogue and digital input functionality, or do more complex tasks such as collecting sensor data via a bus – an I2 example.
C, OneWire, UART or SPI, for
Setup We start by creating a blank App Developer project by selecting ‘new project’ and then the ‘App Developer’ tab, then using the ‘Components Libraries’ toolbar and dragging a CSV Read/Write component from the Storage category and an API (ESP32) component from the API category. T e CSV Read/Write component has a
number of macros to write and read data to and from a fi le on the local hard drive. We must fi rst open a specifi c fi le using the macro OpenFile, which requires a fi lename to be entered, for example “log.csv”. In our App Developer project, we create a new property called “fi lename”, or type a line of text, which allows the app user to specify their own log fi les, as required.
T e OpenFile macro has a second
parameter, which is kept should the existing contents of the fi le be deleted when opening. Again, control over this is passed on to the user by creating another property type, this time with the choice of true or false:
We then call the OpenFile macro,
using the two property variables as macro parameters. We create a Boolean-type variable with name FileOK to store the return, which tells us if the fi le was created/ opened successfully:
Now that the log fi le is open, we can
add data to it by using the AddNumber or AddString macros. Calling these macros adds the specifi ed value to the fi le as an ASCII string of characters, followed by a comma, which automatically moves horizontally from column to column in the CSV fi le. When we want to move downwards onto a new row and back to the fi rst column we use the NextRow macro.
We give the property variable a default
value that will be used when the user fi rst loads the app:
12 November 2021
www.electronicsworld.co.uk T e only other macro we may need to
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