We develop and take a look at functions with the Professional midi 1284P board.
Not too long ago we’ve launched and described a brand new prototyping board referred to as PRO midi 1284, primarily based on an ATmega 1284P microcontroller; after this presentation, made in a earlier submit, we begin to work with it and we clarify interface it in a sensible and quick approach to the exterior world, no less than when it comes to {hardware}. For this goal, on this article, we’ll suggest what, within the perspective of the event platform, is its pure complement, that may be a board created to permit and facilitate the research, growth and debugging of functions primarily based on it. The board in query is the PRO midi 1284P Developer’s Board proven in Fig. 1.
This board offers a housing for the “PRO midi 1284P” and an entire collection of connectors to attach or host numerous digital units (additionally within the type of a breakout board) that help you develop functions that exploit the varied sources of the Atmega1284P, resembling analogue ports, digital ports, serial ports, I²C bus, SPI bus, and so on., and so on..
Fig. 1.
Not solely that, for individuals who need to develop in an MPLAB X setting and carry out each the code loading and the true debugging, there may be additionally a JTAG connector the place to attach a budget SNAP programmer/debugger from Microchip; on this regard, we level out that the board, obtainable from Open Electronics (additionally on-line at www.open-electronics.org) is already assembled however with the 2 LEDs LD1 and LD2 not soldered, however current within the bundle. Those that aren’t inquisitive about utilizing the MPLAB X growth setting and the JTAG programmer/debugger, however intend to make use of the Arduino setting and programming through a serial port by the bootloader, can simply solder these LEDs (respecting the polarity, cathode on the left, anode on the correct, wanting on the board with the ability connector on the left). Then again, if you wish to use JTAG programming and debugging, it will be higher to keep away from soldering these LEDs, since they correspond to the TCK and TMS pins of the JTAG connector and will intrude with right operation.
ELECTRICAL DIAGRAM
On the high you’ll be able to clearly see the ability provide part with the enter (blackjack, high left of the board), the place you’ll be able to apply a voltage from 7V DC to 12V DC, linked first to a 5V voltage regulator after which to a 3.3V voltage regulator. These two voltage regulators present the 2 respective voltages to your entire board.
Be aware that since a number of units may be linked to the board and the ability consumption may be fairly excessive, the next limitations have to be utilized, in any other case some elements could also be broken.
- Don’t energy the “PRO midi 1284P Developer’s Board” by the USB <-> serial adapter current on the “PRO midi 1284P”, however solely by the black Jack. Which means, for those who use Arduino IDE to program the MCU and also you interface through serial with an adapter, you will need to join all pins, besides the +Vcc pin (so you will need to join: GND, TX, RX and RST/DTR, however not +Vcc).
- Restrict the whole absorption (+5V along with +3.3V) to a most of 1,000 mA. Increased absorptions might trigger the 5V regulator to overheat, leading to potential injury.
- The facility provide coming to the MCU is +5V, so all direct I/Os of the Atmega1284P might be with that voltage. There are already some connectors on the board which have stage translators from 5V to three.3V (for instance for the I²C pins).
Just under the ability provide part, on the left aspect, you’ll be able to see two MOSFETs (Q1 and Q2) which have the duty to behave as stage shifters, between +5V and +3,3V, for the alerts going to the I²C bus and to some connectors already ready for a selected use, such because the one to attach a breadboard with a BMP180 sensor (temperature, humidity and atmospheric strain) or these to attach a 0.96″ OLED show (there are two variations of the 0.96″ OLED show and one has the ability pins reversed in comparison with the opposite, so it’s important to be very cautious wherein connector to insert the show).
One other connector permits the connection of different I²C units working at 3.3V, in truth, it makes obtainable the GND pin, the +3.3V pin and the 2 SCL and SDA pins linked to the extent shifter MOSFETs.
Be aware that pull-up resistors for the I²C bus are already current on the board and are linked to the SDA and SCL pins of the MCU (pin 16 and 17 of the “PRO midi 1284P” board).
Persevering with downwards, at all times on the left aspect of the diagram, we discover another connectors. Two of them permit the connection of I²C units working at 5V, whereas the final one on the backside is ready for the insertion of a breadboard with the RTC DS3231 module.
Within the centre of the diagram, there may be the MCU (ATmega1284P microcontroller) that’s mounted on the PRO midi 1284P board and that have to be inserted within the area reserved for it on the PRO midi 1284P Developer’s Board.
Persevering with to look at the diagram of the board, on the correct aspect of the MCU, continuing from high to backside, we discover a connector marked NEOPIXEL, on which connector there are the ability provides, +5V and GND, in addition to pin D0 for use for connecting a strip of LEDs WS2812 or comparable, referred to as NeoPixel.
There may be additionally a connector labelled ANALOG that makes obtainable the analogue inputs A1, A2 and A3 in addition to offering +5V and GND; this can be utilized to attach sensors that present an analogue sign output between 0V and +5V.
Within the wiring diagram we’ve, then, a connector marked APA102; it makes accessible the ability provide line (+5V and GND), in addition to the 2 pins D7 and D5 that can be utilized to manage a strip of LEDs APA102 each with the administration completely software program of the 2 essential alerts (Clock and Information), and delegating this administration to the SPI library with which these LEDs are managed at excessive velocity.
Let’s proceed with the evaluation arriving at trimmer R5, linked on one aspect to +5V and on the opposite to GND, with the cursor linked to analogue enter A0. This trimmer can be utilized to study the operation of an analogue port, in truth, whenever you rotate the slider from proper to left, the worth returned by the perform analogRead (A0) of Arduino, will differ from 0 to 1023 in a proportional approach to the worth of voltage current on that pin A0.
A connector marked “SPI” that makes obtainable the MOSI (D5), SCK (D7), MISO (D6) and SS (D4) pins, along with the standard +5V and GND, to attach objects that speak to the microcontroller by the SPI bus. If you don’t use the SPI bus, a few of these pins can be utilized with the “Servo” library to drive servomotors. Within the latter case, we advocate that you simply seek the advice of Desk 1, which exhibits the correspondence between the interior timers and their contacts on the board.
Desk 1
The circuit has two pushbuttons named P1 and P2, full with R/C debouncing community, linked respectively to digital inputs D15 and D14; for his or her use understand that these buttons are near the bottom (LOW worth of Arduino). To be able to use them, they have to be outlined in this system as inputs with an energetic pull-up resistor, or, utilizing the Arduino syntax, you will need to make the: pinMode(pin, INPUT_PULLUP) in order that, when the button will not be pressed, the enter may have a excessive worth (HIGH), whereas when the button is pressed, it’s going to have a low worth (LOW).
Just under these buttons, within the diagram, we discover the JTAG connector. The use or not of such connector is a perform of the event setting that’s supposed to make use of.
For many who will work in a pure Arduino setting, with the usage of the IDE and programming through serial port, by the usage of the exterior converter USB <-> Serial, and the “bootloader” current within the “PRO midi 1284P”, this JTAG connector will serve solely to have obtainable pins D18, D19, D20 and D21 along with the RESET pin and energy provide, +5V and GND.
For many who will work within the MPLAB X setting of Microchip, this JTAG connector will make obtainable all of the alerts for the usage of a programmer/debugger as SNAP, that’s, along with the ability provide +5V and GND, additionally the alerts of TCK, TDI, TMS and RESET. Be aware that the connector on the board is straight connectable to the aforementioned SNAP programmer, with a straight 7-conductor cable because the pin place is similar because the programmer connector.
Lastly, on the backside of the circuit below the JTAG connector, we discover 4 light-emitting diodes, recognized by the initials LD1, LD2, LD3 and LD4. As talked about earlier, solely the 2 LEDs LD3 and LD4 might be soldered on the board, whereas the remaining two LEDs, LD1 and LD2, might be provided unsoldered. Will probably be as much as the end-user to decide on whether or not to depart solely two LEDs on the board or to mount all 4, relying on whether or not or not the JTAG programmer/debugger is used. To be able to facilitate low-level programming, we present in Desk 2 the correspondence of among the pins used within the PRO midi 1284P Developer’s Board.
Desk 2
Fig. 2 exhibits the association of the described connectors. The serigraphy on the board clearly signifies the which means of every single pin. As it’s clear from the supply of connectors each generic (SPI, I÷C, ANALOG, and so on.) and particular (OLED Show, RTC DS3231, BMP180 module, and so on.) the PRO midi 1284P Developer’s Board permits to make use of of all of the sources of the Atmega1284P and to study the use and programming of them permitting the experimentation on the usage of numerous extra {hardware} elements.
Fig. 2
Fig. 3 exhibits the event board with the PRO midi 1284 and an RTC module put in; as an alternative in Fig. 4 you see the board utilized to an Arduino Mega (by advantage of the presence of the strips on the underside, which match the Arduino Mega headers), simply to offer you an thought of the flexibility of the event system that it kinds with the ProMidi 1284P.
Fig. 3
Fig. 4
Record of Parts:
R1, R2, R3, R4: 4,7 Kohm
R5: Trimmer 10 Kohm MV
R6, R7: 1kohm
R8, R9, R10, R11, R12: 470 ohms
C1, C7, C9: 100 F 35 VL Electrolytic
C2, C5, C6, C8: 100 nF Ceramic
C3, C4: 100 nF 100 VL polyester
LD1: 5 mm LED inexperienced (see textual content)
LD2 LED 5 mm yellow (see textual content)
LD3 LED 5 mm pink
LD4 LED 5 mm inexperienced
P1, P2: Microswitch
Q1, Q2: BS170
BMP180: BMP180 module
OLED1: OLED show 0.96″ I2C
LCD: I2C LCD show
DS3231: DS3231 RTC Module
SERVO: Servomotor 6V
NEOPIXEL: LED WS2812B
APA102: LED APA102
D1: 1N4007
U1: 7805
U2: MCP1702-3302E/TO
Varied:
– Strip feminine 3-way (1 laptop.)
– Strip feminine 4 methods (7 pcs.)
– Strip feminine 5 methods (1 laptop.)
– Strip feminine 6 methods (2 pcs.)
– Strip feminine 7 methods (1 laptop.)
– Strip feminine 20 methods (2 pcs)
– Strip Arduino 8 methods (5 pcs.)
– Strip Arduino 10 methods (1 laptop.)
– Arduino strip 2×18 methods (1 laptop.)
– Energy provide plug
– PCB S1393 (102×73 mm)
FROM OPENSTORE
Professional Midi 1284P
PRO midi 1284P Developer’s Board
Show Oled 1.3 inch
Breakout with DS3231 & EEPROM
