add simplest I2C on G070 (next will be through DMA)

G0:G070/i2c/i2c.c

@@ -0,0 +1,196 @@
+/*
+ * This file is part of the i2cscan project.
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm32g0.h>
+#include "usart.h"
+#include "i2c.h"
+
+/*
+ * GPIO Resources: I2C1_SCL - PB6 (AF6), I2C1_SDA - PB7 (AF6)
+ */
+
+I2C_SPEED curI2Cspeed = LOW_SPEED;
+extern volatile uint32_t Tms;
+static uint32_t cntr;
+volatile uint8_t I2C_scan_mode = 0; // == 1 when I2C is in scan mode
+static uint8_t i2caddr  = I2C_ADDREND; // current address in scan mode
+
+void i2c_setup(I2C_SPEED speed){
+    if(speed >= CURRENT_SPEED){
+        speed = curI2Cspeed;
+    }else{
+        curI2Cspeed = speed;
+    }
+    RCC->IOPENR |= RCC_IOPENR_GPIOBEN;
+    I2C1->CR1 = 0;
+    GPIOB->AFR[0] = (GPIOB->AFR[0] & ~(GPIO_AFRL_AFSEL6 | GPIO_AFRL_AFSEL7)) |
+            6 << (6 * 4) | 6 << (7 * 4);
+    GPIOB->MODER = (GPIOB->MODER & ~(GPIO_MODER_MODE6 | GPIO_MODER_MODE7)) |
+                    GPIO_MODER_MODER6_AF | GPIO_MODER_MODER7_AF;
+    GPIOB->OTYPER |= GPIO_OTYPER_OT6 | GPIO_OTYPER_OT7; // both open-drain outputs
+    // I2C (default timing from PCLK - 64MHz)
+    RCC->APBENR1 |= RCC_APBENR1_I2C1EN; // clocking
+    if(speed == LOW_SPEED){ // 10kHz
+        // PRESC=F, SCLDEL=4, SDADEL=2, SCLH=0xC3, SCLL=0xC7
+        I2C1->TIMINGR = (0xF<<28) | (4<<20) | (2<<16) | (0xC3<<8) | (0xC7);
+    }else if(speed == HIGH_SPEED){ // 100kHz
+        I2C1->TIMINGR = (0xF<<28) | (4<<20) | (2<<16) | (0xF<<8) | (0x13);
+    }else{ // VERYLOW_SPEED - the lowest speed by STM register: ~7.7kHz
+        I2C1->TIMINGR = (0xF<<28) | (4<<20) | (2<<16) | (0xff<<8) | (0xff);
+    }
+    I2C1->CR1 = I2C_CR1_PE;
+}
+
+/**
+ * write command byte to I2C
+ * @param addr - device address (TSYS01_ADDR0 or TSYS01_ADDR1)
+ * @param data - bytes to write
+ * @param nbytes - amount of bytes to write
+ * @param stop - to set STOP
+ * @return 0 if error
+ */
+static uint8_t write_i2cs(uint8_t addr, uint8_t *data, uint8_t nbytes, uint8_t stop){
+    cntr = Tms;
+    I2C1->CR1 = 0; // clear busy flag
+    I2C1->ICR = 0x3f38; // clear all errors
+    I2C1->CR1 = I2C_CR1_PE;
+    while(I2C1->ISR & I2C_ISR_BUSY){
+        IWDG->KR = IWDG_REFRESH;
+        if(Tms - cntr > I2C_TIMEOUT){
+            USND("Line busy\n");
+            return 0;  // check busy
+    }}
+    cntr = Tms;
+    while(I2C1->CR2 & I2C_CR2_START){
+        IWDG->KR = IWDG_REFRESH;
+        if(Tms - cntr > I2C_TIMEOUT){
+        return 0; // check start
+    }}
+    //I2C1->ICR = 0x3f38; // clear all errors
+    I2C1->CR2 = nbytes << 16 | addr;
+    if(stop) I2C1->CR2 |= I2C_CR2_AUTOEND; // autoend
+    // now start transfer
+    I2C1->CR2 |= I2C_CR2_START;
+    for(int i = 0; i < nbytes; ++i){
+        cntr = Tms;
+        while(!(I2C1->ISR & I2C_ISR_TXIS)){ // ready to transmit
+            IWDG->KR = IWDG_REFRESH;
+            if(I2C1->ISR & I2C_ISR_NACKF){
+                I2C1->ICR |= I2C_ICR_NACKCF;
+                //USND("NAK\n");
+                return 0;
+            }
+            if(Tms - cntr > I2C_TIMEOUT){
+                USND("Timeout\n");
+                return 0;
+            }
+        }
+        I2C1->TXDR = data[i]; // send data
+    }
+    // wait for data gone
+    while(I2C1->ISR & I2C_ISR_BUSY){
+        IWDG->KR = IWDG_REFRESH;
+        if(Tms - cntr > I2C_TIMEOUT){break;}
+    }
+    return 1;
+}
+
+uint8_t write_i2c(uint8_t addr, uint8_t *data, uint8_t nbytes){
+    return write_i2cs(addr, data, nbytes, 1);
+}
+
+/**
+ * read nbytes of data from I2C line
+ * all functions with `addr` should have addr = address << 1
+ * `data` should be an array with at least `nbytes` length
+ * @return 1 if all OK, 0 if NACK or no device found
+ */
+static uint8_t read_i2cb(uint8_t addr, uint8_t *data, uint8_t nbytes, uint8_t busychk){
+    if(busychk){
+        cntr = Tms;
+        while(I2C1->ISR & I2C_ISR_BUSY){
+            IWDG->KR = IWDG_REFRESH;
+            if(Tms - cntr > I2C_TIMEOUT){
+                USND("Line busy\n");
+                return 0;  // check busy
+        }}
+    }
+    cntr = Tms;
+    while(I2C1->CR2 & I2C_CR2_START){
+        IWDG->KR = IWDG_REFRESH;
+        if(Tms - cntr > I2C_TIMEOUT){
+            USND("No start\n");
+            return 0; // check start
+    }}
+    // read N bytes
+    I2C1->CR2 = (nbytes<<16) | addr | 1 | I2C_CR2_AUTOEND | I2C_CR2_RD_WRN;
+    I2C1->CR2 |= I2C_CR2_START;
+    uint8_t i;
+    for(i = 0; i < nbytes; ++i){
+        cntr = Tms;
+        while(!(I2C1->ISR & I2C_ISR_RXNE)){ // wait for data
+            IWDG->KR = IWDG_REFRESH;
+            if(I2C1->ISR & I2C_ISR_NACKF){
+                I2C1->ICR |= I2C_ICR_NACKCF;
+                USND("NAK\n");
+                return 0;
+            }
+            if(Tms - cntr > I2C_TIMEOUT){
+                USND("Timeout\n");
+                return 0;
+            }
+        }
+        *data++ = I2C1->RXDR;
+    }
+    return 1;
+ }
+
+uint8_t read_i2c(uint8_t addr, uint8_t *data, uint8_t nbytes){
+    return read_i2cb(addr, data, nbytes, 1);
+}
+
+// read register reg
+uint8_t read_i2c_reg(uint8_t addr, uint8_t reg, uint8_t *data, uint8_t nbytes){
+    if(!write_i2cs(addr, &reg, 1, 0)) return 0;
+    return read_i2cb(addr, data, nbytes, 0);
+}
+
+// read 16bit register reg
+uint8_t read_i2c_reg16(uint8_t addr, uint16_t reg16, uint8_t *data, uint8_t nbytes){
+    if(!write_i2cs(addr, (uint8_t*)&reg16, 2, 0)) return 0;
+    return read_i2cb(addr, data, nbytes, 0);
+}
+
+void i2c_init_scan_mode(){
+    i2caddr = 0;
+    I2C_scan_mode = 1;
+}
+
+// return 1 if next addr is active & return in as `addr`
+// if addresses are over, return 1 and set addr to I2C_NOADDR
+// if scan mode inactive, return 0 and set addr to I2C_NOADDR
+int i2c_scan_next_addr(uint8_t *addr){
+    *addr = i2caddr;
+    if(i2caddr == I2C_ADDREND){
+        *addr = I2C_ADDREND;
+        I2C_scan_mode = 0;
+        return 0;
+    }
+    if(!read_i2c_reg((i2caddr++)<<1, 0, NULL, 0)) return 0;
+    return 1;
+}