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