Using Sipeed TANG PriMER [3] – I2C / SPI with RISC-V

Tang Primer
In the previous article, I wrote the RISC-V core on the FPGA and set up the environment to develop software with Arduino IDE.
Bluish-purple tech
Using Sipeed TANG PriMER [2] - RISC-V development with Arduino IDE
https://mytoolbox.tech/tec/en/2022/01/19/sipeed_tang_primer_arduino_e/
In the previous article, we have set up the environment of the TANG PriMER FPGA development board from SiPeed, and have confirmed the logic synthesis and writing of the samples.In this article, we will start to synthesize the RISC-V processor, write it to the FPGA, build the software using Arduino IDE, and write it to the ROM on the board.TANG PriMER FPGA development boardLogic Synthesis of RISC-V E203 Core and Writing to FPGAThe first step is to synthesize the RISC-V core (Tang_E203_Mini). D...
In this article, I will try to control the I/O of this RISC-V processor to run external devices.
TANG PriMER FPGA Development Board

Try to use SPI
First, let’s use the SPI interface. The device to be connected is the EEPROM made by ROHM, which was used in this article.BR25L320 device
Bluish-purple tech
Using the Raspberry Pi Pico [6] - SPI communication with Micro Python
https://mytoolbox.tech/tec/en/2021/12/28/rspi_pico_spi_mpython_e/
SPI on the Raspberry Pi PicoThe RP2040 has two independent SPI controllers (SPI0 / SPI1), available on the Raspberry Pi Pico from GP to GP pins. In this article, I tried to use this feature to connect the LCD display and read/write the EEPROM.Connecting the ATM0130B3 LCDThe ATM0130B3 is a 240x(RGB)x240 1.3-inch full-color graphic LCD. This time, we used Akizuki's control kit with 2.54mm pitch conversion board to connect it. The pitch conversion board also has a level conversion circuit, ...

Hardware
The I/O pins on the TANG PriMER board correspond to the SPI signals as shown below. Note that only the SPI MOSI signal is not connected to the 2.54mm pitch pins on the board, and needs to be pulled out from the outer half-pitch header. Also, the SPI CS signal is implemented using GPIOs as shown in the program below.
Lichee Tang PinSPI signal
B14SCLK
B10MISO
P4MOSI

Software
The following program is built on the ArduinoIDE to confirm that the EEPROM address 0x01AB is read after writing data 0xAA. The CS, WP, and HOLD signals of EEPROM are implemented with E203 GPIO. 
#include <SPI.h>

const int SPI_CS   = 2;
const int SPI_WP   = 3;
const int SPI_HOLD = 4;

void setup()
{
  pinMode(SPI_CS,   OUTPUT);
  pinMode(SPI_WP,   OUTPUT);
  pinMode(SPI_HOLD, OUTPUT);
  digitalWrite(SPI_CS,   HIGH);
  digitalWrite(SPI_WP,   LOW);
  digitalWrite(SPI_HOLD, LOW);

Serial.begin(19200);
while (!Serial);

SPI.begin();
}

void loop()
{
  byte data[5];
  data[0] = 0x06;
  spi_write_byte(data, 1);

data[0] = 0x02;
  data[1] = 0x01;
  data[2] = 0xAB;
  data[3] = 0xAA;
  spi_write_byte(data, 4);

data[0] = 0x04;
  spi_write_byte(data, 1);

delay(100);

data[0] = 0x03;
  data[1] = 0x01;
  data[2] = 0xAB;
  spi_read_byte(data, data, 3);

Serial.println(data[3], HEX);

delay(2000);           // wait  seconds for next scan
}

void spi_read_byte(byte *wdata, byte *rdata, byte length) 
{
    int i;

digitalWrite(SPI_CS,   LOW);
  digitalWrite(SPI_WP,   HIGH);
  digitalWrite(SPI_HOLD, HIGH);

for( i = 0; i < length; i++ ) {<br />
    SPI.transfer( wdata[i] );
  }
  rdata[i] = SPI.transfer( 0x00 );

digitalWrite(SPI_CS,   HIGH);
  digitalWrite(SPI_WP,   LOW);
  digitalWrite(SPI_HOLD, LOW);

return rdata[i];
}

void spi_write_byte(byte *data, int length) 
{
  int i;
  digitalWrite(SPI_CS,   LOW);
  digitalWrite(SPI_WP,   HIGH);
  digitalWrite(SPI_HOLD, HIGH);

for( i = 0; i < length; i++ ) {
    SPI.transfer( data[i] );
  }

digitalWrite(SPI_CS,   HIGH);
  digitalWrite(SPI_WP,   LOW);
  digitalWrite(SPI_HOLD, LOW);
}


Try to use I2C
Next, I would like to try using I2C, but currently the hardware I2C of the E203 is not supported by the Arduino IDE, and it seems that the only way to implement it is with software I2C (The I2C circuit seems to be implemented in the RTL of the E203, so I would like to try it in a different environment later.
The following is an example of an implementation using software I2C functions. The device to be connected is the TMP102 temperature sensor used in the following article.
Bluish-purple tech
Using the Raspberry Pi Pico [5] - I2C communication with Micro Python
https://mytoolbox.tech/tec/en/2021/12/27/rspi_pico_i2c_mpython_e/
I2C on the Raspberry Pi PicoThe RP2040 has two independent channels of I2C controllers (I2C0 / I2C1), which are available on the Raspberry Pi Pico from GP to GP pins. In this article, we tried to use this feature to read and write the digital temperature sensor and EEPROM.Connecting the TMP102 digital temperature sensor moduleThe TMP102 device is a high-precision digital temperature sensor made by TI, with a built-in 12-bit ADC, a minimum resolution of 0.0625°C, and an accuracy of ±0.5°C with...


Hardware
The I/O pins and I2C signals on the TANG PriMER board are matched as follows. Since this is a software I2C, the pins to be used can be set by software.
Lichee Tang PinI2C signal
J11SCL
F16SDA


Software
Create the following program on the ArduinoIDE and write it. 
#include <SlowSoftWire.h>

SlowSoftWire Wire = SlowSoftWire(18, 19, true);

void setup()
{
  Wire.begin();

Serial.begin(19200);
  while (!Serial);<br />
  Serial.println("nI2C Scanner");
}

void loop()
{
  byte error, address; 
  byte tmp102 = 0;
  int nDevices;

Serial.println(F("Scanning I2C bus (7-bit addresses) ..."));

nDevices = 0;
  for(address = 1; address < 127; address++ ) {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

if (error == 0) {
    Serial.print(F("I2C device found at address 0x"));
    if (address<16)
      Serial.print(F("0"));
    Serial.print(address, HEX);
    Serial.println(F("  !"));

nDevices++;

if(address == 0x48) {
  tmp102 = 1;
}
else {
  tmp102 = 0;
}

}
else if (error==4) {
    Serial.print(F("Unknown error at address 0x"));
    if (address<16)
      Serial.print("0");
    Serial.println(address,HEX);
}

}

if (nDevices == 0) {
    Serial.println("No I2C devices foundn");
  }
  else { 
    Serial.println("donen");

if(tmp102 == 1) {
  uint8_t data[2];
  Wire.requestFrom(0x48, 2, 1); 
  data[0]= Wire.read();
  data[1]= Wire.read();
  Serial.print(F("TMP102 data : 0x")); Serial.print(data[0], HEX); Serial.print(F(" 0x"));  Serial.print(data[1], HEX);
  Serial.println(F(""));
}

}

delay(2000);           // wait 2 seconds for next scan
}
Scan the I2C address to find a device that responds, and if the TMP102 device (slave address 0x48) is among them, it will acquire temperature data. If the temperature is displayed via the serial monitor, the communication is successful.

References

https://qiita.com/Nanchite4618/items/62ff04e3345519b3a939

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