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BLANK PCB ONLY 28-pin Microchip PIC DIP & RS232 3.3V/5V Regulator Module

Location: /Kits, Sets/PCB

BLANK PCB ONLY 28-pin Microchip PIC DIP & RS232 3.3V/5V Regulator Module

Click image to zoom.

Shown images are ilustrative only. Please refer to manufacturer's website and/or available datasheet for accurate information.

QtyUnit PriceLot Price
1C$2.0100C$2.01
10C$1.3600C$13.60
30 mul:15C$1.0600C$31.80
Stock:123 ships next workday

This PCB is for microcontroller module with RS232 connector, transceiver, 3.3/5V voltage regulator and in application programmable 28-pin PIC. Module fits into breadboard or standard DIP32 0.6in socket, supports two most common types of DB9 connectors, parasitic power from RS232 and CPU voltage is configurable via solder jump. Sale is for PCB only, see schematic for more details. Buy only if you understand text below as we cannot help you build it nor provide support for this item.

Product Information
dipmicro Code DE3597
Manufacturer dipmicro
Manufacturer P/N DP117S
Stock Type New
Restockable? No
Shipping Weight 4.0g / 0.141oz
Ship Cost Canada CP O/S Letter C$4
Ship Cost USA USPS First Class $4

Schematic

Click the images to zoom.

As the bare minimum, the circuitry around U1 is installed. This will provide a RS232/UART converter.

The voltage regulator U2 collects power from RTS/TXD/DTR signals via D1/D2. This will work only when one of these signals is on. RS232 specification allows minimum 3V, but most usual are 5 (USB converters) or 12V. There must be at least 5V from the serial port in order to collect enough power.

When relying on parasitic power, the MAX232 or derivatives is not most suitable for the job, since it requires 8mA for operation (3-5mA other derivatives). If you are going to use this device with parasitic power, use MAX3232, which is pin compatible replacement with wider voltage range and requires only 0.3mA for full operation. However, if you will provide external power, the 8mA part will be just fine. Just do not forget that some parts need 1uF capacitors while others will work with 0.1uF.

The microcontroller can be any SOIC28 type PIC16/PIC18 that has VDD/VSS/RX/TX/MCLR pins compatible with PIC16F886-I/SO (e.g. PIC18F26K20-I/SO). If you will be running on parasitic power, lower-power part will be more suitable and do not expect to get full 16 MIPS out of it. The design provides VDD/GND/RX/TX signals + 16 I/O pins on the headers. Also there is an extra 3 pins beside RB7 that provide ICSP port for initial flashing (not meant to be populated by headers).

There is room for modification - for example the unconnected portion of D2 can be used for unregulated external voltage (e.g. 12V) up to 0.2A - use 10uF electrolytic cap as C1 in that case..

Circuit Board

This revision requires jumper on bottom side as shown below.


Top side, click to zoom.

Bottom side, click to zoom.

Top Copper, click to zoom.

Bottom Copper, click to zoom.

Parts

No parts are critical and you are welcome to use drawer parts you have on hand. For example in the prototype we substituted C1,C8 and C9 by through-hole parts, LED1 was PLCC2 part we already had. See our prototype below. It should be also easy to mount TO92 version of LM317.


Click image to zoom.

PartDescription
C11206 ceramic or tantalum, 0.1uF ~ 10uF
C21206 ceramic or tantalum 10uF (see U2 datasheet)
C3-60603 ceramic 0.1uF ~ 1uF (see U1 datasheet)
C70603 ceramic 0.1uF
C8,90603 ceramic 22pF (see U3 datasheet)
D1,2SOT23 diode arrays (e.g. BAT54C) - only for parasitic power option
D3SOD523 schottky diode, not necessary, short with jumper
H1,210-pin headers
H3,4optional, no function
LED10805 green LED but it's possible to mount PLCC2 using a nearby via
P1,29-pin DB9, P1 is right-angle, P2 is solder-cup edge mount
Q1HC49US low profile (see your selected U3 datasheet)
R10603 3k3 (parasitic power option only)
R20603 8k2 (parasitic power option only)
R30603 15k (parasitic power option, second voltage only)
R40603 680R for ~5mA LED drive, 3k9 for ~1mA with brigh LED
R50603 1-10k (see U3 datasheet). At least 5x value of R4 if D3 shorted
U1SOIC16 MAX232/ST232/SP232/SP202/MAX3232/ST3232/etc
U2SOT223 LM317/LM1117/SPX1117/etc
U3SOIC28 PIC16F88x-I/SO, PIC18F26K22-I/SO, etc