ch32_oled/ssd1306_i2c.h

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2024-04-07 00:46:58 +02:00
/*
* Single-File-Header for SSD1306 I2C interface
* 05-07-2023 E. Brombaugh
*/
#ifndef _SSD1306_I2C_H
#define _SSD1306_I2C_H
#include <string.h>
// SSD1306 I2C address
#define SSD1306_I2C_ADDR 0x3c
// I2C Bus clock rate - must be lower the Logic clock rate
#define SSD1306_I2C_CLKRATE 1000000
// I2C Logic clock rate - must be higher than Bus clock rate
#define SSD1306_I2C_PRERATE 2000000
// uncomment this for high-speed 36% duty cycle, otherwise 33%
#define SSD1306_I2C_DUTY
// I2C Timeout count
#define TIMEOUT_MAX 100000
// uncomment this to enable IRQ-driven operation
//#define SSD1306_I2C_IRQ
#ifdef SSD1306_I2C_IRQ
// some stuff that IRQ mode needs
volatile uint8_t ssd1306_i2c_send_buffer[64], *ssd1306_i2c_send_ptr, ssd1306_i2c_send_sz, ssd1306_i2c_irq_state;
// uncomment this to enable time diags in IRQ
//#define IRQ_DIAG
#endif
/*
* init just I2C
*/
void ssd1306_i2c_setup(void)
{
uint16_t tempreg;
// Reset I2C1 to init all regs
RCC->APB1PRSTR |= RCC_APB1Periph_I2C1;
RCC->APB1PRSTR &= ~RCC_APB1Periph_I2C1;
// set freq
tempreg = I2C1->CTLR2;
tempreg &= ~I2C_CTLR2_FREQ;
tempreg |= (FUNCONF_SYSTEM_CORE_CLOCK/SSD1306_I2C_PRERATE)&I2C_CTLR2_FREQ;
I2C1->CTLR2 = tempreg;
// Set clock config
tempreg = 0;
#if (SSD1306_I2C_CLKRATE <= 100000)
// standard mode good to 100kHz
tempreg = (FUNCONF_SYSTEM_CORE_CLOCK/(2*SSD1306_I2C_CLKRATE))&SSD1306_I2C_CKCFGR_CCR;
#else
// fast mode over 100kHz
#ifndef SSD1306_I2C_DUTY
// 33% duty cycle
tempreg = (FUNCONF_SYSTEM_CORE_CLOCK/(3*SSD1306_I2C_CLKRATE))&SSD1306_I2C_CKCFGR_CCR;
#else
// 36% duty cycle
tempreg = (FUNCONF_SYSTEM_CORE_CLOCK/(25*SSD1306_I2C_CLKRATE))&I2C_CKCFGR_CCR;
tempreg |= I2C_CKCFGR_DUTY;
#endif
tempreg |= I2C_CKCFGR_FS;
#endif
I2C1->CKCFGR = tempreg;
#ifdef SSD1306_I2C_IRQ
// enable IRQ driven operation
NVIC_EnableIRQ(I2C1_EV_IRQn);
// initialize the state
ssd1306_i2c_irq_state = 0;
#endif
// Enable I2C
I2C1->CTLR1 |= I2C_CTLR1_PE;
// set ACK mode
I2C1->CTLR1 |= I2C_CTLR1_ACK;
}
/*
* error descriptions
*/
char *errstr[] =
{
"not busy",
"master mode",
"transmit mode",
"tx empty",
"transmit complete",
};
/*
* error handler
*/
uint8_t ssd1306_i2c_error(uint8_t err)
{
// report error
printf("ssd1306_i2c_error - timeout waiting for %s\n\r", errstr[err]);
// reset & initialize I2C
ssd1306_i2c_setup();
return 1;
}
// event codes we use
#define SSD1306_I2C_EVENT_MASTER_MODE_SELECT ((uint32_t)0x00030001) /* BUSY, MSL and SB flag */
#define SSD1306_I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED ((uint32_t)0x00070082) /* BUSY, MSL, ADDR, TXE and TRA flags */
#define SSD1306_I2C_EVENT_MASTER_BYTE_TRANSMITTED ((uint32_t)0x00070084) /* TRA, BUSY, MSL, TXE and BTF flags */
/*
* check for 32-bit event codes
*/
uint8_t ssd1306_i2c_chk_evt(uint32_t event_mask)
{
/* read order matters here! STAR1 before STAR2!! */
uint32_t status = I2C1->STAR1 | (I2C1->STAR2<<16);
return (status & event_mask) == event_mask;
}
#ifdef SSD1306_I2C_IRQ
/*
* packet send for IRQ-driven operation
*/
uint8_t ssd1306_i2c_send(uint8_t addr, uint8_t *data, uint8_t sz)
{
int32_t timeout;
#ifdef IRQ_DIAG
GPIOC->BSHR = (1<<(3));
#endif
// error out if buffer under/overflow
if((sz > sizeof(ssd1306_i2c_send_buffer)) || !sz)
return 2;
// wait for previous packet to finish
while(ssd1306_i2c_irq_state);
#ifdef IRQ_DIAG
GPIOC->BSHR = (1<<(16+3));
GPIOC->BSHR = (1<<(4));
#endif
// init buffer for sending
ssd1306_i2c_send_sz = sz;
ssd1306_i2c_send_ptr = ssd1306_i2c_send_buffer;
memcpy((uint8_t *)ssd1306_i2c_send_buffer, data, sz);
// wait for not busy
timeout = TIMEOUT_MAX;
while((I2C1->STAR2 & I2C_STAR2_BUSY) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(0);
// Set START condition
I2C1->CTLR1 |= I2C_CTLR1_START;
// wait for master mode select
timeout = TIMEOUT_MAX;
while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_MODE_SELECT)) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(1);
// send 7-bit address + write flag
I2C1->DATAR = addr<<1;
// wait for transmit condition
timeout = TIMEOUT_MAX;
while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(2);
// Enable TXE interrupt
I2C1->CTLR2 |= I2C_CTLR2_ITBUFEN | I2C_CTLR2_ITEVTEN;
ssd1306_i2c_irq_state = 1;
#ifdef IRQ_DIAG
GPIOC->BSHR = (1<<(16+4));
#endif
// exit
return 0;
}
/*
* IRQ handler for I2C events
*/
void I2C1_EV_IRQHandler(void) __attribute__((interrupt));
void I2C1_EV_IRQHandler(void)
{
uint16_t STAR1, STAR2 __attribute__((unused));
#ifdef IRQ_DIAG
GPIOC->BSHR = (1<<(4));
#endif
// read status, clear any events
STAR1 = I2C1->STAR1;
STAR2 = I2C1->STAR2;
/* check for TXE */
if(STAR1 & I2C_STAR1_TXE)
{
/* check for remaining data */
if(ssd1306_i2c_send_sz--)
I2C1->DATAR = *ssd1306_i2c_send_ptr++;
/* was that the last byte? */
if(!ssd1306_i2c_send_sz)
{
// disable TXE interrupt
I2C1->CTLR2 &= ~(I2C_CTLR2_ITBUFEN | I2C_CTLR2_ITEVTEN);
// reset IRQ state
ssd1306_i2c_irq_state = 0;
// wait for tx complete
while(!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_BYTE_TRANSMITTED));
// set STOP condition
I2C1->CTLR1 |= I2C_CTLR1_STOP;
}
}
#ifdef IRQ_DIAG
GPIOC->BSHR = (1<<(16+4));
#endif
}
#else
/*
* low-level packet send for blocking polled operation via i2c
*/
uint8_t ssd1306_i2c_send(uint8_t addr, uint8_t *data, uint8_t sz)
{
int32_t timeout;
// wait for not busy
timeout = TIMEOUT_MAX;
while((I2C1->STAR2 & I2C_STAR2_BUSY) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(0);
// Set START condition
I2C1->CTLR1 |= I2C_CTLR1_START;
// wait for master mode select
timeout = TIMEOUT_MAX;
while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_MODE_SELECT)) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(1);
// send 7-bit address + write flag
I2C1->DATAR = addr<<1;
// wait for transmit condition
timeout = TIMEOUT_MAX;
while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(2);
// send data one byte at a time
while(sz--)
{
// wait for TX Empty
timeout = TIMEOUT_MAX;
while(!(I2C1->STAR1 & I2C_STAR1_TXE) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(3);
// send command
I2C1->DATAR = *data++;
}
// wait for tx complete
timeout = TIMEOUT_MAX;
while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_BYTE_TRANSMITTED)) && (timeout--));
if(timeout==-1)
return ssd1306_i2c_error(4);
// set STOP condition
I2C1->CTLR1 |= I2C_CTLR1_STOP;
// we're happy
return 0;
}
#endif
/*
* high-level packet send for I2C
*/
uint8_t ssd1306_pkt_send(uint8_t *data, uint8_t sz, uint8_t cmd)
{
uint8_t pkt[33];
/* build command or data packets */
if(cmd)
{
pkt[0] = 0;
pkt[1] = *data;
}
else
{
pkt[0] = 0x40;
memcpy(&pkt[1], data, sz);
}
return ssd1306_i2c_send(SSD1306_I2C_ADDR, pkt, sz+1);
}
/*
* init I2C and GPIO
*/
uint8_t ssd1306_i2c_init(void)
{
// Enable GPIOC and I2C
RCC->APB2PCENR |= RCC_APB2Periph_GPIOC;
RCC->APB1PCENR |= RCC_APB1Periph_I2C1;
// PC1 is SDA, 10MHz Output, alt func, open-drain
GPIOC->CFGLR &= ~(0xf<<(4*1));
GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_OD_AF)<<(4*1);
// PC2 is SCL, 10MHz Output, alt func, open-drain
GPIOC->CFGLR &= ~(0xf<<(4*2));
GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_OD_AF)<<(4*2);
#ifdef IRQ_DIAG
// GPIO diags on PC3/PC4
GPIOC->CFGLR &= ~(0xf<<(4*3));
GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*3);
GPIOC->BSHR = (1<<(16+3));
GPIOC->CFGLR &= ~(0xf<<(4*4));
GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*4);
GPIOC->BSHR = (1<<(16+4));
#endif
// load I2C regs
ssd1306_i2c_setup();
#if 0
// test if SSD1306 is on the bus by sending display off command
uint8_t command = 0xAF;
return ssd1306_pkt_send(&command, 1, 1);
#else
return 0;
#endif
}
/*
* reset is not used for SSD1306 I2C interface
*/
void ssd1306_rst(void)
{
}
#endif