DuinoCoinI2C_RPI

This project design to mine Duino-Coin using Raspberry Pi or equivalent SBC as a master and Arduino/ATtiny85 as a slave.

Using the I2C communication to connect all the boards and make a scalable communication between the master and the slaves.

Video Tutorial

Raspberry Pi AVR I2C Bus 1 tutorial video

Raspberry Pi AVR I2C Bus 0 tutorial video

Raspberry Pi Pico HW Part1 tutorial video

Raspberry Pi Pico SW Part2 tutorial video

Python Environment Setup

Linux

sudo apt update
sudo apt install python3 python3-pip git i2c-tools python3-smbus screen -y # Install dependencies
git clone https://github.com/JK-Rolling/DuinoCoinI2C_RPI.git # Clone DuinoCoinI2C_RPI repository
cd DuinoCoinI2C_RPI
python3 -m pip install -r requirements.txt # Install pip dependencies

Use sudo raspi-config to enable I2C. Refer detailed steps at raspberry-pi-i2c

For RPI I2C Bus 0, extra step is needed, sudo nano /boot/config.txt and add dtparam=i2c_vc=on, save and reboot

For RPi Pico as worker, the RPi master is strongly recomended to use 400kHz/1MHz SCL clock frequency. again, sudo nano /boot/config.txt, add dtparam=i2c_baudrate=1000000 and dtparam=i2c_vc_baudrate=1000000 for 1MHz. Change to 400000 if you prefer 400kHz SCL.

Finally, connect your I2C AVR miner and launch the software (e.g. python3 ./AVR_Miner_RPI.py)

Windows

1. Download and install Python 3 (add Python and Pip to Windows PATH)
2. Download the DuinoCoinI2C_RPI
3. Extract the zip archive you've downloaded and open the folder in command prompt
4. In command prompt type py -m pip install -r requirements.txt to install required pip dependencies

Finally, connect your I2C AVR miner and launch the software (e.g. python3 ./AVR_Miner_RPI.py or py AVR_Miner_RPI.py in the command prompt)

Version

DuinoCoinI2C_RPI Version 3.3

Arduino - Slave

Arduino shall use DuinoCoin_RPI_Tiny_Slave sketch. LLC is required if Arduino is operating at 5V and master at 3.3V. Arduino also have builtin temperature sensor that can be used for IoT reporting. This feature is enabled for fun as the ADC is uncalibrated. Once calibrated, the temperature can be pretty accurate according to some. Set TEMPERATURE_OFFSET and FILTER_LP to calibrate.

Occasionally slaves might hang and not responding to master. quick workaround is to press the reset button on the slave to bring it back.

Once in a blue moon, one of the slave might pull down the whole bus with it. power cycling the rig is the fastest way to bring it back.

To solve these issues permanently, update Nano with Optiboot bootloader. WDT will auto reset the board if there is no activity within 8s.

Change this line to true to activate the WDT. works for Nano clone as well. make sure the Nano is using Optiboot

#define WDT_EN true

feature can be turn on/off individually to cater for your specific scenario. set to false to disable.

#define I2CS_FIND_ADDR false
#define WDT_EN true
#define CRC8_EN true
#define LED_EN true
#define SENSOR_EN true

#define	Note
DEV_INDEX	device index to help assign I2C address
I2CS_START_ADDRESS	this and DEV_INDEX summation will produce final I2C address
I2CS_FIND_ADDR	Scan available I2CS address and self-assign, overriding DEV_INDEX. Recommend to set false
WDT_EN	Auto self-reset every 8s in case of inactivity
CRC8_EN	I2C CRC8 insertion and data integrity checks
LED_EN	Blink when share is found
SENSOR_EN	Report chip internal temperature in degree Celsius

each SBC have different starting I2CS address from i2cdetect command. Address that is not shown is still usable. To change the I2CS starting address, modify I2CS_START_ADDRESS

For disabled I2CS_FIND_ADDR, manually assign I2CS address by updating DEV_INDEX. I2CS_FIND_ADDR is best effort basis, it may or may not work.

ATtiny85 - Slave

Use DuinoCoin_ATTiny_Slave for ATtiny. LLC is required if worker and host is operating at different voltage. 4k7 pullup resistors for SDA/SCL pins are strongly recommended if host do not have it built-in. The TWI/I2C/IIC seems to work well with SCL 100KHz WIRE_CLOCK 100000. Default compiled sketch size for ATtiny85 is 5630 bytes for program storage space and 351 bytes for dynamic memory. Estimated hashrate 267H/s for ATTiny85-20PU running at 3.3V or 5V. ATTiny85 also have builtin temperature sensor that can be used for IoT reporting. This feature is enabled for fun as the ADC is uncalibrated. Once calibrated, the temperature can be pretty accurate according to some. Set TEMPERATURE_OFFSET and TEMPERATURE_COEFF to calibrate. Note: floating point is costly, only proceed if you know what you're doing.

add http://drazzy.com/package_drazzy.com_index.json to Additional Board Manager URLs in Arduino IDE, then go to board manager and search for attiny and install ATTinyCore from Spence Konde

ATTiny85 for example, the system clock is default at 1MHz. This needs to be changed to get good hashrate

You may use dedicated ATTiny programmer or any Uno/Nano to set the fuse via Tools --> Burn Bootloader. See table below on setting that worked for me on ATtiny85. Finally upload sketch using Sketch --> Upload Using Programmer

Attribute	Value
Board	ATtiny25/45/85 (No Bootloader)
Chip	ATtiny85
Clock Source	16.5 MHz (PLL,tweaked)
Timer 1 Clock	CPU
LTO	Enabled
millis()/micros()	Enabled
Save EEPROM	EEPROM retained
B.O.D Level	Disabled

ATTiny85 Wiring

Reducing sketch / RAM usage

For some smaller devices, to get smallest possible sketch size without hacking, set CRC8_EN false, WDT_EN false, SENSOR_EN false and change to #pragma GCC optimize ("-Os") for all files. You should get 4232 bytes use of program storage space and 343 bytes of dynamic memory, which produce about 222H/s at 16MHz

to get smallest possible sketch size with hacking, use the above settings and hack file Arduino15\packages\ATTinyCore\hardware\avr\1.5.2\libraries\Wire\src\USI_TWI_Slave\USI_TWI_Slave.h. This should further reduce the dynamic memory usage to 319 bytes. RELIABILITY NOT GUARANTEED

// change value from 16 to 4. somehow value of 1/2 broke TWI
#define TWI_RX_BUFFER_SIZE (4)
#define TWI_TX_BUFFER_SIZE (4)

Adafruit Trinket ATtiny85 - Slave

Similar to ATtiny85, but Trinket came with bootloader which leave only 5310 Bytes for sketch. Use DuinoCoin_Tiny_Slave_trinket sketch to start mining. Estimated hashrate at 258 H/s, consuming 97% of available program space (5146 Bytes).

VBAT+ pin on the Trinket 5V will accept 3.3V input just fine, so LLC not required if the master is using 3.3V logic level.

Removing bootloader

You may use Arduino Nano/Uno or ATtiny programmer to remove the bootloader to regain full 8KB storage, load DuinoCoin_ATTiny_Slave instead to get 267 H/s (+3.5%)

Load File > Examples > ArduinoISP into Uno/Nano and connect as below. Open DuinoCoin_ATTiny_Slave, choose the Uno/Nano from Tools > Port, choose Tools > Programmer > Arduino as ISP, finally, Sketch > Upload Using Programmer

Trinket		Uno/Nano
VBAT+	<--->	5V
GND	<--->	GND
RST	<--->	#10
#0	<--->	#11
#1	<--->	#12
#2	<--->	#13

Repair bootloader

Follow the wiring in Removing bootloader, download the trinketloader_2015-06-09.zip, extract all files, load the trinketloader into Uno/Nano, open Serial console at 9600 baudrate, hit G and enter. bootloader should be uploaded into the Trinket and once again, sketch can be uploaded into Trinket via USB

Raspberry Pi Pico - Slave

Use Pico dual core code for Raspberry Pi Pico. Logic Level Converter (LLC) is not required as both RPi and Pico operates at 3.3V.

Read kdb.ino for detailed setup steps in Arduino IDE

RP2040 board package from Earle F. Philhower, III

For good out-of-box experience, add https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json to Additional Board Manager URLs in Arduino IDE, then search for RP2040 Boards version 2.2.1 or above. Install it from Arduino IDE board manager

Default I2C pin SDA0 - GP20 SCL0 - GP21 SDA1 - GP26 SCL1 - GP27

Relocating I2C pins

User can change the I2C pin by modifying pin value in DuinoCoin_RPI_Pico_DualCore.ino

#define I2C0_SDA 20 #define I2C0_SCL 21 #define I2C1_SDA 26 #define I2C1_SCL 27

The motivation to change the default I2C pin is to make the board rig building friendly because now the I2C pin have the same side as the Vsys pin

Library Dependency

• ArduinoUniqueID (Handle the chip ID)
• StreamString

I2C Address

The I2C Address on the Arduino is hardcoded by user. if an address already exists on the I2C bus, the behavior is undefined

Change the value on the define for each worker for unique address:

#define DEV_INDEX 1

Raspberry PI or SBC - Master

The master requests the job on the DuinoCoin server and sends the work to the slave (Arduino).

After the job is done, the slave sends back the response to the master (SBC) and then sends back to the DuinoCoin server.

IoT Feature

RPi Pico have built in temperature sensor that made IoT reporting possible.

For other worker, it is possible to add external sensor and enhance worker sketch to read them. But it is outside of the scope.

CRC8 Feature

During setup, Python will auto discover worker CRC8 status. This option applies to all workers.

CRC8 feature is ON by default. To disable it, use #define CRC8_EN false

Max Client/Slave

The code theoretically supports up to 119 clients on Raspberry PI (Bullseye OS) on single I2C bus

Slave addresses range from 0x0..0x77

Some reported that I2C addresses that did not shows up from i2cdetect are accessible

RPi have 2 I2C buses which bring up the count up to 254 (theoretical). This requires 2 separate instances of Python miner with it's own Settings.cfg file. Duplicate the directory into 2 and start the setup from there. Instance 1 should use i2cbus 1 (RPi have builtin 1k8 pullup). Instance 2 should use i2cbus 0 (where external 4k7 pullup resistor are on)

Enable I2C on Raspberry PI

Google or refer to raspberry-pi-i2c

For RPI I2C Bus 0, there might not be pull up resistor built in. It relies on the pull up from Nano.

For other I2C slave that do not have pull up capability, add 4k7 Ohm resistor to both SDA and SCL line on I2C bus 0.

Note: If you see bad shares, it could be due to a bug in RPI I2C hardware

Connection Pinouts

Connect the pins of the Raspberry PI on the Arduino like the table/images below, use a Logic Level Converter to connect between the SBC and Arduino/ATtiny85

	RPI	Logic Level Converter	Arduino
	3.3V	<--->	5V
	GND	<--->	GND
SDA	PIN 3	<--->	A4
SCL	PIN 5	<--->	A5

	RPI	Logic Level Converter	ATtiny85
	3.3V	<--->	5V
	GND	<--->	GND
SDA	PIN 3	<--->	PB0
SCL	PIN 5	<--->	PB2

For dual I2C master and dual I2C slave interface

	RPI (dual I2C)		Pico
	3.3V or 5V	<--->	VSYS*
	GND	<--->	GND
SDA1	PIN 3	<--->	GP26
SCL1	PIN 5	<--->	GP27
SDA0	PIN 27	<--->	GP20
SCL0	PIN 28	<--->	GP21

For single I2C master and dual I2C slave interface

	RPI (single I2C)		Pico
	3.3V or 5V	<--->	VSYS*
	GND	<--->	GND
SDA1	PIN 3	<--->	GP26, GP20
SCL1	PIN 5	<--->	GP27, GP21

* VSYS accept voltage range from 1.8V to 5.5V. Voltage regulator onboard Pico will generate 3.3V for rp2040 use

Benchmarks of tested devices

Device	Average hashrate (all threads)	Mining threads
Arduino Pro Mini, Uno, Nano etc. (Atmega 328p/pb/16u2)	268 H/s	1
Adafruit Trinket 5V Attiny85	258 H/s	1
Attiny85	267 H/s	1
Raspberry Pi Pico	4.7 kH/s (100MHz)	2
Raspberry Pi Pico	5.4 kH/s (120MHz)	2

License and Terms of service

All refers back to original Duino-Coin licensee and terms of service