Testing of sensors with RS485 using PC without proper interface is not possible. Since RS232 interfaces are very rare, the interface should be hooked to USB. The interface between USB and RS485 can be soldered with one of the many FTDI interfaces with added RS485 driver, or bought as assembled module. There is always the third option. I made it from scratch.
I took smallest STM32F0 with USB and UART interface. The best thing with UART in the STM32F0 is that signal for driver enable is provided within hardware. The complete pinout of the microcontroller is:
Continue reading ‘USB to RS485’ »
This is simple, small interface between USB and alphanumeric LCD with 16×2 characters. It is using CDC class – Virtual COM port.
Microcontroller is from STM32 cortex M0 value line family: STM32F070F6. This small “gizmo” has very attractive price and good choice of peripheral devices, like ADC, USB, plenty of timers, etc… Really nice device in “DIY-friendly” package – TSSOP20.
Continue reading ‘USB to Alphanumeric LCD interface’ »
This LPC1700 prototyping board is modular and simple to build as single-sided PCB. I made it with toner-transfer method. No drilling is required, just SMD soldering. Complete board is modular. Normally, not all periphery is used all the time. Depending on project, there are just too many possibilities, which can not be covered by a single prototyping board. This schematic is just one example how to use miniature prototyping modules, which are described in other posts. Such modules have one big dvantage: they can be simply recycled and used in many prototypes. This protoboard is populated with USB and JTAG modules as absolute minimum for start debugging. USB module provides 3,3V power supply from USB port and JTAG interface is for debugging.
Other modules provided on this board are:
- ethernet PHY
- Micro SD socket
- Monochrome 128×64 graphical LCD
- 16 bit ADC
- 24 bit ADC
- audio amplifier
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Many micro-controller circuits are powered from the USB port. Supply voltage is usually less than USB five volts. Supply circuit has adjustable output voltage with few jumpers. Some circuits require two supply voltages, one for digital part and second for analog part. Jumpers and resistors are selected such that when no jumper is inserted, the output voltage will be at minimum level. This prevents electronic circuit from damage when jumpers are forgotten. It’s shown in schematic:
Continue reading ‘Universal USB port adapter with regulator’ »