Low-level APIs for controlling embedded devices

Local and remote

When thinking about remote I/O devices, and customers’ needs, we think of different classes of device:

• Local: Local devices connect to a PC using USB or Bluetooth.
• Remote: Remote devices connect to a PC using Wi-fi, LAN or the internet.

Defined function and Flexible function

Local and remote devices can be off-the-shelf devices or can be custom made. Some connected devices will have defined functions – for example a remote thermostat, or an Ethercat connected sensor– and others will have flexible functions - for example a Labjack input output controller. Flexible function devices have an Application Programming Interface – API – that allows developers to design electronic systems.

Open source and closed source API

Some flexible function devices have a closed source APIs – for example the LabJack. This can not be edited. Other devices have open source code and you can edit the code and make the device behave as you wish. A good example of this is the Arduino, MIAC, ESP32 and other Matrix products: the APIs are written in Flowcode embedded and you are free to edit them.

Defined function (AllCode) API devices

There are many of these. Immediately available from Matrix are the following:

Hardware Platform	MIAC PIC	MIAC AllCode	Formula AllCode	Robot Arm v2
MCU Type	PIC	dsPIC	dsPIC	dsPIC
Slave Type	AllCode	AllCode	AllCode	AllCode
Communications
USB	Y	Y	Y	Y
Bluetooth		Y	Y	Y
WIFI		Y		Y
Programming
Programming Method	mLoader	mLoader	mLoader	PC Loader
USB	Y	Y	Y	Y
Bluetooth			Y
Firmware	Firmware	Firmware	Firmware	Firmware
Component Source	Component Source
Examples	Examples	Examples	Examples	Examples
USB Driver	USB Driver	USB Driver		USB Driver
Basic I/O
Digital Input Pins	8	8
Motor Output Pins	4	4
Relay Output Pins	4	4		1
Analogue Input Pins	8	8
Protection	Y	Y
Features
UART/RS232/RS485/Modbus		1
CAN	1	1
PWM	2	4
Display	Y	Y	Y
Sensors			1	1
Motors			2	4

These products have defined functions which simplifies their use: the I/O is defined by function not by pin output. This allows the creator to have an API command like ‘MOTOR 100’ rather than to define the PWM rate and then define which outputs are on.

Flexible function (SCADA Slave) API devices

Immediately available from Matrix are the following:

Hardware Platform	Arduino Uno	Arduino Mega	ECIO28P	ECIO40P	E-blocks2 BL0032	Raspberry Pi	ESP32	Interface Board
MCU Type	AVR	AVR	PIC	PIC	dsPIC	Linux	ESP32	PIC
Slave Type	SCADA Slave	SCADA Slave	SCADA Slave	SCADA Slave	SCADA Slave	SCADA Slave	SCADA Slave	SCADA Slave
Communications
USB	Y	Y	Y	Y	Y		Y	Y
Bluetooth								Y
WIFI						Y	Y	Y
Programming
Programming Method	AVRdude	AVRdude	mLoader	mLoader	mLoader	SD Card / SSH	ESP IDF	PICkit
USB	Y	Y	Y	Y	Y		Y	Y
WIFI / Ethernet						Y	Y
Firmware	Firmware		Firmware	Firmware				Firmware
Component Source								Component Source
Examples	Examples		Examples	Examples				Examples
USB Driver								USB Driver
Basic I/O
Digital I/O Pins	14	54	19	30	47	26	32	17
Analogue Output Pins					2		1	1
Analogue Input Pins	6	16	10	14	13		14	3
Features
SPI	1	1	1	1	4	1	1	1
I2C	1	1	1	1		1	2	1
UART/RS232/RS485/Modbus		3	1	1	6	1	3	1
CAN					2
Bluetooth					1	1	1	1
WIFI					1	1	1	1
Ethernet/TCPIP/Modbus TCP						1
PWM	6	16	2	2	27	2	2	2

The source code for all of these is available – so you can manufacture your own local and remote flexible function device for use with Flowcode App Developer.

Using an API device in App Developer

Fixed Function devices

1. Connect the device to the PC via USB. Start a new App Developer programme. You may be able to load a template for the device which will preserve the settings in Flowcode and save you some time.

2. You will need to ensure that you have the appropriate driver installed

3. Open a 2D Dashboard panel. Select COMPONENT LIBRARIES…..API

4. Click and drag a ,for example, MIAC Allcode API onto the panel.

5. In Project Explorer click on Components and you will see the API icons that you can use to construct your program.

6. Construct the program

7. Select DEBUG…Go and your program should run on the slave device.

Flexible function devices

For example with Arduino Uno

1. Take an Arduino, Connect it to the PC using USB. You will need to ensure that you have the appropriate driver installed

2. Load the Flowcode API programme for the Arduino Uno into Flowcode Embedded and compile it to the Arduino. Your Uno with flexible function API is now ready for use.

3. Start a new App Developer programme. You may be able to load a template for the device which will preserve the settings in Flowcode and save you some time.

4. Open a 2D Dashboard panel. Select COMPONENT LIBRARIES…..API

5. Click and drag a SCADA(Arduino uno) API onto the panel.

6. In Project Explorer click on Components and you will see the API icons that you can use to construct your program.

7. Construct the program

8. Select DEBUG…Go and your program should run on the slave device.

Additional API device examples

Matrix App Developer supports by default a selection of hardware devices with a built in API. Some devices have a basic or built in API and will not need firmware loading on to them, such as the PS2000 oscilloscope or K8055D Velleman I/O board. Other devices will need a API firmware loading on to them to allow the PC SCADA application to communicate with the firmware API. Most of the API's come as open source projects.

Device	Manufacturer	Comms	Description	Embedded Firmware	Component Source Project	Runtime Example Project	USB Driver
FTD2XX	FTDI	USB	General purpose USB driver chip	N/A	Available on request	Examples	FTDI Website
K8055D	Velleman	USB	General purpose USB I/O board	N/A	Available on request	Examples	Velleman Website
PS2000	Pico Technology	USB	Oscilloscope	N/A	Available on request	Examples	Picotech Website
PL155-P	TTI	USB	Power supply	N/A	Available on request	Examples	TTI Website
TG5011	TTI	USB	Signal generator	N/A	Available on request	Examples	TTI Website