The development board is made in order to help the work of hardware and programmers in creating and writing software for a specific hardware version of real projects in electronics and programming.
the variant of the board that is presented contains links to the main hardware module of the processor board. the board with the processor is placed on the development board by means of rails soldered, and if desired, another option can be chosen for mounting the processor board to the development board. to this board there is designed and manufactured a set of boards with connectors for development for the various hardware modules designed in the board of the processor. as shown in the picture, the board has several communication ports, ADC / analog to digital converter / 3 channels, two ports for digital sensors widely used in practice, 8 ports for direct digital input-output and free soldering contact pads convenient for use in development activity in electronics programming.
technical description of the development board:
1. power supply input voltage + 12V - stabilized
2. supply voltage after the stabilizer 7805 -> + 5V
3. The processor board has its own stabilized power supply of + 3.3V, which is made by the manufacturer. on the board / processor / is given an input for + 5V, which we use to power the system. !!!!!! PLEASE NOTE THAT THE OUTPUTS AND INPUTS ARE WITH OPERATING VOLTAGE + 3.3V !!!!!!!!!!!!!.
this requires the use of resistor voltage dividers AT THE INPUTS TO THE CPU BOARD so that when using + 5V input data you DO NOT BURN THE PINS OF THE PROCESSOR !!!! such resistive dividers can be seen on the development board at the DS18B20 temperature sensor as well as at the DHT11 combined humidity and temperature sensor. the third resistor divider is on the SPI / communication / communication port to which different peripheral boards of the same set are provided for connection. There are links to the site in other categories. I will also give direct links to the description of the other boards in the kit in the description below on this board.
4. input / output ports - ULN2803 - there are 8 input / output ports to the development board, and an output driver board with 8 ports, chip number ULN2803 is provided. the board with the driver is also designed and manufactured by me, and with it you can easily start designing a specific electronic circuit and writing software for each project with 8 LEDs. this is a fairly easy option for starting a development activity for beginners in electronics and programming with PI PICO, as by connecting and starting the driver board with 8 LEDs they will be able to program and check the whole process of starting basic software for PI PICO. the same port will have a board for use as inputs, as we have already said, there must be resistor dividers for each input pin of the processor board, so as not to burn the CPU pin when applying an input signal greater than + 3.3V !! !! There will be an example of connecting and launching the driver board later, I can also make a video of how to start a board with 8 LEDs connected to the development board and writing the software for the LEDs.
5. standard serial port RS232 with location of the pins for CH340 converter with input from USB to serial port RS232 / photo on the board /
6. through this port with / without the converter, as well as with any other console USB <=> RS232 you can communicate to any computer program of the type standard serial RS232 terminal. if you can make your own serial terminal program for windows, if you can't download from the internet any that supports this standard for serial RS232 communication.
7. SPI port for communication with other boards in the set and / or your own development boards and systems. The SPI port is directly connected to the CPU board, and the MISO input pin is separated by a resistor divider, which reduces the voltage from + 5V to + 3.3V so as not to burn the RPI2040 processor pin.
the location of the connection port pins are made in two uses of the SPI port. OPTION 1 >> hardware SPI port can be used directly from the hardware module of the processor board. in the description of the RPI2040 the PICO board has the location of 4 communication pins in the SPI port. if you use an SPI peripheral board connected to the development board, you will need the description of the port on the processor board, as well as a diagram of the location of the pins on the development board, which I will give on the site.
The RPI2040 hardware SPI port software can be found on the PI PICO website, and there are enough libraries on the Internet for this communication standard and its use for other SPI chips and peripherals. The RPI2040 hardware SPI port software can be found on the PI PICO website, and there are enough libraries on the Internet for this communication standard and its use for other SPI chips and peripherals.
OPTION 2 >> use of the SPI port in a software version connected to the standard GPIO input / output pins. so, there is a slightly more complex software library here, and it's easier for the hardware solution. you can connect the pins of a SPI chip directly to the GPIO pins, by software telling the RPI2040 processor which pin to be MOSI, MISO, CS, CLK. this software SPI variant of communication I use it constantly both in PIC processors and in RPI2040 PI PICO processor.
the software for the software variant of SPI is several functions bigger, as you have to determine in advance which pin of 4 connected will be CS, CLK, MOSI, MISO. as you know the MISO input of the RPI2040 is the output of the SPI specific chip and there must be a resistor divider for + 3.3V. then you need to configure it as an input because for the chip connected to the board it is an output. this pin transmits the data from the connected chip to the processor at command and given pulses to the CLK. everyone who uses SPI communication knows how it works, for those who have not yet used this standard there is a lot of info on the net.
I have provided several boards with SPI communication in different variants, both with LEDs, which can be considered as relays, and buttons, which can be considered as inputs from other systems.
The SPI boards I have designed and manufactured for this development board will be described in the other categories. one variant for SPI << ADC, three variant of expansion boards with MCP23S17 expansion chip. variants of this chip are a board with 16 buttons, a board with 16 LEDs, a board with 8 + 8 buttons with LEDs. description in other categories of the site.
8. DS18B20 digital temperature sensor input port. this input is separated by a resistor divider because the digital temperature sensor has only one pin through which commands are transmitted to the sensor, as well as the reception of temperature data and other functions. There are many software libraries on the Internet for this sensor, widely used in many applications.
9. direct port for combined humidity and temperature sensor DHT11. this sensor also has one pin communication, also with a resistor divider, the difference is that there are 4 pins for mounting, but one is not used in an electrical connection. description and software abound on the net, albeit for other processors.
10. ADC / analog-to-digital conversion / of input signals from sensors to RPI2040. on the processor board there are 3 pins for the ADC port, which are output directly to the development board. On the photo, as well as on the prototype board, I have mounted 10 kiloohm trimmers for testing the hardware ADC unit, but whoever wants can solder any sensors with analog output, and in advance in the software you have to set these pins to be INPUT ANALOG PINS !!! !!
11. for all who have another task for hardware and software, they can use the rails on the board with the description of the pins, by soldering cables to them, for connection with external systems in the electronics.
DON'T FORGET, THE INPUTS OF THE RPI2040 ARE VOLTAGE 3.3V !!!!!! YOU NEED RESISTOR DIVISORS SO YOU DON'T BURN THE PINS !!!! READ THE RPI2040 CPU BOARD DOCUMENTATION NOT TO SMOKE THE CPU !!!! DON'T FORGET AGAIN !!!! THE OUTPUTS ARE ALSO AT + 3.3V !!!! Which means if you want to directly connect MOSFET TRANSISTORS WILL NOT unblock 100 PER CENT AND WILL need to use ULN2803 driver stage connected to + 5V and after TO CONNECT MOSFET transistors BIGGER voltages LOADS !!! IN ANOTHER ARTICLE I WILL SHOW WITH A SCHEME AND A BOARD AND A DESCRIPTION !!!!!