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After I developed and published a Transistor Curvetracer based on the Arduino NANO R3 a few years ago, I analyzed the datasheet for the Arduino NANO-R4 and came up with the idea of developing an improved and simpler Curvetracer based on it The higher CPU speed and expanded memory of the R4 also make it possible to use displays with (320x480 pixels) and sizes of 3.5 or 4 inches instead of the previously used display (240x320 pixels) with a maximum size of 3.2 inches.

On the ARDUINO R3 I had to use an external DAC (MCP4822) and ADCs(MCP3402) with 12 bit because the NANO R3 has no DAC and the ADCs have  only 10 bit. resolution.

I see the following key differences between the NANO R3 and R4 for this project:

   Integrated 12-bit DAC on pin A0

   improved ADCs (from 10-bit to 14-bit)

   more flexible use of internal interrupts

   higher CPU speed (16 MHz vs. 48 MHz)

   significantly larger memory (Flash and RAM)


I  thought it would be easy to change ..., eliminate the external DAC and ADC.

But it wasn't.


And I investigate some time for Touch functions.

For low bias currents of 10 µA, the MCP3402 ADCs  I used on Arduino NANO R3

is the biggest problem; the display flickers around the curve.


The Arduino Nano R4's internal 14-bit ADC promises better results in this regard.


I made two new boards  (KiCad) for the NANO R4 and
a new amplifier board (for Uce ) inclusive power supplies  +19V, +7.5V,+5V and -5V.

On the NANO R4 board, I’ve routed all the pins—some of them multiple times—and included a socket for the 24LC256 EEPROM, as well as voltage dividers for the ILI9341 SPI display and for the ADCs A1, A2, and A3. 

in addition to the TCA0372 amplifier, the Uce Board includes four TLP222A electronic switches (or equivalent), which connect the emitter (n-type devices) or collector (p-type devices) to the current-sensing resistor, 
as well as various power supplies:
 I

-    +19V - 22V for the TCA0372   
-       -5V    for the TCA0372 (clean waveforms around zero)
-  +7.5V    to generate the -5V
-   +5V      for the Arduino Nano R4, the display, 
                and the isolated constant-current board for driving the base or gate.

I think this is the most complex project that has been implemented with the NANO-R4 so far:


- SPI interface for the display (and external DAC)

- I2C interface for EEPROM (and external DAC)

- Touch functionality

- Internal interrupts for 2 encoders (currently only one is in use) and push-button switches

-  Bluetooth for communication with PC or  smartphone (not currently implemented)

- Saving data to an SD card (not currently implemented)