/* * geany_encoding=koi8-r * i2c.c * * Copyright 2017 Edward V. Emelianov * * 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 2 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, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, * MA 02110-1301, USA. * */ #include "stm32f0.h" #include "i2c.h" /** * I2C for HTU21D * Speed <= 400kHz (200) * t_SCLH ~ 0.6us * t_SCLL ~ 1.3us * t_SU >= 100ns * t_HD <= 900ns * t_VD <= 400ns * * After start 15ms pause for IDLE * Start bit: SCK=1, DATA 1->0 * Stop bit: SCK 0->1, DATA 0->1 * Address: 0x40 (7bit), 0th bit - direction (0 - write, 1 - read) * ACK: DATA->0 on 8th SCK clock * Commands: 0xE3[F3] - temperature, 0xE5[F5] - humidity [No hold master] * 0xE6 - write user register, 0xE7 - read user register, 0xFE - soft reset * 7 6 5 4 3 2 1 0 * User register: |D1|Vbat|reserved|Htr|Odis|D0| default: 0x02 * D1D0 - resolution [H/T]: 00-12/14, 01-8/12, 10-10/13, 11-11/11 * Vbat=1 vhen Vdd<2.25V, Htr=1 to enable on-chip heater, * Odis=0 to enable OTP reload (after each measurement reload defaults) * * in = in & 0xFFFC; * Calculations: RH = -6 + 125*Hum/2^16 * T = -46.85 + 175.72*Temp/2^16 */ /* * Resources: I2C1_SCL - PA9, I2C1_SDA - PA10 * GPIOA->AFR[1] AF4 -- GPIOA->AFR[1] &= ~0xff0, GPIOA->AFR[1] |= 0x440 */ extern volatile uint32_t Tms; static uint32_t cntr; void i2c_setup(){ // GPIO RCC->AHBENR |= RCC_AHBENR_GPIOAEN; // clock GPIOA->AFR[1] &= ~0xff0; // alternate function F4 for PA9/PA10 GPIOA->AFR[1] |= 0x440; GPIOA->OTYPER |= GPIO_OTYPER_OT_9 | GPIO_OTYPER_OT_10; // opendrain GPIOA->MODER &= ~(GPIO_MODER_MODER9 | GPIO_MODER_MODER10); GPIOA->MODER |= GPIO_MODER_MODER9_AF | GPIO_MODER_MODER10_AF; // alternate function // I2C RCC->APB1ENR |= RCC_APB1ENR_I2C1EN; // timing RCC->CFGR3 |= RCC_CFGR3_I2C1SW; // use sysclock for timing // Clock = 6MHz, 0.16(6)us, need 5us (*30) // PRESC=4 (f/5), SCLDEL=0 (t_SU=5/6us), SDADEL=0 (t_HD=5/6us), SCLL,SCLH=14 (2.(3)us) I2C1->TIMINGR = (4<<28) | (14<<8) | (14); // 0x40000e0e I2C1->CR1 = I2C_CR1_PE;// | I2C_CR1_RXIE; // Enable I2C & (interrupt on receive - not supported yet) } // I2C2->TIMINGR = (uint32_t)0x00B01A4B; // PRECS=0 - tpresc=20.8(3)ns, SCLDEL=B (tSU 12tpresc), SDADEL=0 (tHD=0), SCLH=1a (27), SCLL=4B (76) // https://github.com/mattbrejza/magnet-node/blob/master/firmware-basestation/htu21.c // prescaler = 1, low period = 0x13, high period = 0xf, hold time = 2, setup = 4 // I2C_TIMINGR(H_I2C) = (1<<28) | (4<<20) | (2<<16) | (0xf<<8) | 0x13; /* transmit: * I2Cx_CR2: * Addressing mode (7-bit or 10-bit): ADD10 * Slave address to be sent: SADD[9:0] * Transfer direction: I2C_CR2_RD_WRN=0 * The number of bytes to be transferred: NBYTES[7:0] (NBYTES<<16) * You must then set the START bit in I2Cx_CR2 register. * Automatic end mode (AUTOEND = '1' in the I2Cx_CR2 register), * I2C1->CR2 = I2C_CR2_HEAD10R | SLAVE_ADDR; // 7bit, slave address */ // return 1 if all OK, 0 if NACK uint8_t htu_write_i2c(uint8_t data){ cntr = Tms; while(I2C1->ISR & I2C_ISR_BUSY) if(Tms - cntr > 5) return 0; // check busy cntr = Tms; while(I2C1->CR2 & I2C_CR2_START) if(Tms - cntr > 5) return 0; // check start I2C1->CR2 = 1<<16 | HTU21_ADDR | I2C_CR2_AUTOEND; // 1 byte, autoend // now start transfer I2C1->CR2 |= I2C_CR2_START; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_TXIS)){ // ready to transmit if(I2C1->ISR & I2C_ISR_NACKF){ I2C1->ICR |= I2C_ICR_NACKCF; return 0; } if(Tms - cntr > 5) return 0; } I2C1->TXDR = data; // send data return 1; } #define SHIFTED_DIVISOR 0x988000 //This is the 0x0131 polynomial shifted to farthest left of three bytes // check CRC, return 0 if all OK uint32_t htu_check_crc(uint16_t data, uint8_t crc){ uint32_t remainder = (uint32_t)data << 8; remainder |= crc; uint32_t divsor = (uint32_t)SHIFTED_DIVISOR; int i; for(i = 0; i < 16; i++) { if (remainder & (uint32_t)1 << (23 - i)) remainder ^= divsor; divsor >>= 1; } return remainder; } // return 1 if all OK, 0 if NACK uint8_t htu_read_i2c(uint16_t *data){ uint8_t buf[3]; cntr = Tms; while(I2C1->ISR & I2C_ISR_BUSY) if(Tms - cntr > 5) return 0; // check busy cntr = Tms; while(I2C1->CR2 & I2C_CR2_START) if(Tms - cntr > 5) return 0; // check start // read three bytes I2C1->CR2 = 3<<16 | HTU21_ADDR | 1 | I2C_CR2_AUTOEND | I2C_CR2_RD_WRN; I2C1->CR2 |= I2C_CR2_START; int i; cntr = Tms; for(i = 0; i < 3; ++i){ while(!(I2C1->ISR & I2C_ISR_RXNE)){ // wait for data if(I2C1->ISR & I2C_ISR_NACKF){ I2C1->ICR |= I2C_ICR_NACKCF; return 0; } if(Tms - cntr > 5) return 0; } buf[i] = I2C1->RXDR; } *data = (buf[0] << 8) | buf[1]; if(htu_check_crc(*data, buf[2])) return 1; // CRC error return 1; } // return 0 if all OK uint8_t htu_read_reg(uint8_t *data){ cntr = Tms; while(I2C1->ISR & I2C_ISR_BUSY) if(Tms - cntr > 5) return 0; // check busy cntr = Tms; while(I2C1->CR2 & I2C_CR2_START) if(Tms - cntr > 5) return 0; // check start I2C1->CR2 = 1<<16 | HTU21_ADDR; // 1 byte I2C1->CR2 |= I2C_CR2_START; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_TXIS)){ // ready to transmit if(I2C1->ISR & I2C_ISR_NACKF){ I2C1->ICR |= I2C_ICR_NACKCF; return 0; } if(Tms - cntr > 5) return 0; } I2C1->TXDR = HTU21_READ_REG; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_TC)) if(Tms - cntr > 5) return 0; // wait transfer completion I2C1->CR2 = 1<<16 | HTU21_ADDR | 1 | I2C_CR2_RD_WRN | I2C_CR2_AUTOEND; // receive, autoend I2C1->CR2 |= I2C_CR2_START; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_RXNE)){ // wait for data if(I2C1->ISR & I2C_ISR_NACKF){ I2C1->ICR |= I2C_ICR_NACKCF; return 0; } if(Tms - cntr > 5) return 0; } *data = I2C1->RXDR; return 1; } uint8_t htu_write_reg(uint8_t data){ cntr = Tms; while(I2C1->ISR & I2C_ISR_BUSY) if(Tms - cntr > 5) return 0; // check busy cntr = Tms; while(I2C1->CR2 & I2C_CR2_START) if(Tms - cntr > 5) return 0; // check start I2C1->CR2 = 1<<16 | HTU21_ADDR; // 1 byte I2C1->CR2 |= I2C_CR2_START; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_TXIS)){ // ready to transmit if(I2C1->ISR & I2C_ISR_NACKF){ I2C1->ICR |= I2C_ICR_NACKCF; return 0; } if(Tms - cntr > 5) return 0; } I2C1->TXDR = HTU21_WRITE_REG; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_TC)) if(Tms - cntr > 5) return 0; // wait transfer completion I2C1->CR2 |= I2C_CR2_AUTOEND; // receive, autoend I2C1->CR2 |= I2C_CR2_START; cntr = Tms; while(!(I2C1->ISR & I2C_ISR_TXIS)){ // ready to transmit if(I2C1->ISR & I2C_ISR_NACKF){ I2C1->ICR |= I2C_ICR_NACKCF; return 0; } if(Tms - cntr > 5) return 0; } I2C1->TXDR = data; return 1; } //output in Cx10 int16_t convert_temperature(uint16_t in){ in = in & 0xFFFC; uint32_t a = (uint32_t)in * 17572; a >>= 16; int16_t val = ((int16_t)a - 4685)/10; return val; } //output in %x10 int16_t convert_humidity(uint16_t in){ in = in & 0xFFFC; uint32_t a = (uint32_t)in * 1250; a >>= 16; int16_t val = (int16_t)a - 60; return val; }