/* (CC-BY-NC-SA) ROBIN KRENS - ROBIN @ ROBINKRENS.NL
*
* $LOG$
- * 2019/7/25 - ROBIN KRENS
+ * 2019/8/14 - ROBIN KRENS
* Initial version
*
* $DESCRIPTION$
- * Basic driver for the TM1637. The TM1637 is 7 segment
- * ledclock peripheral. Communication is over I2C.
+ * Driver for the TM1637 for STM32 boards.
+ * The TM1637 is (4 digit) 8 segment ledclock peripheral. Communication
+ * is similar to I2C, but not completely. There is no device address
+ * selecting. Instead, you can directly send a command / write data.
+ *
+ * Most libraries for this chip that I have seen use 'Bit banging'.
+ * Manually adjusting the clock and data pin (not using the I2C)
+ *
+ * This driver is different and uses STM32 I2C hardware. A problem of the
+ * TM1637 chip, however, is that commands sometimes set bit 1 (LSB). Setting
+ * the LSB will make the STM32 MCU switch to receiver mode. (A better design
+ * choice for commands would have to keep the LSB reserved).
+ *
+ * Another thing to note is that this chip uses BIG-ENDIANESS
*
* */
#include <lib/regfunc.h>
#include <lib/string.h>
+#include <lib/tinyprintf.h>
#include <drivers/tm1637.h>
+#define TIMEOUT 5000
-void tm1637_init() {
+#define DOT true
+#define NODOT false
- /* Program the peripheral input clock in I2C_CR2 Register in order to generate correct timings
- Configure the clock control registers
- Configure the rise time register
- Program the I2C_CR1 register to enable the peripheral
- Set the START bit in the I2C_CR1 register to generate a Start condition
+#define WRITE_CMD 0x20
- ENABLE GPIOB6 and B7*/
+/* STM32F1 microcontrollers do not provide the ability to pull-up SDA and SCL lines. Their
+GPIOs must be configured as open-drain. So, you have to add two additional resistors to
+pull-up I2C lines. Something between 4K and 10K is a proven value.
+*/
- //regw_u8(RCC_APB1ENR, 0x1, 21, SETBIT);
- //regw_u32(RCC_APB2ENR, 0x1, 3, SETBIT);
- // //regw_u8(AFIO_EVCR, 0x89, 0, SETBIT);// set event control register, output on ?
-
- // regw_u32(GPIOB_CRL, 0xEE444444, 0, OWRITE);
+void tm1637_init() {
+
+ /* Program the peripheral input clock generate correct timings.
+ * Configure the clock control registers CCR
+ * Configure the rise time register TRIS
+ * Program the I2C_CR1 register to enable the peripheral
+ * Enable GPIOB6 and B7*/
+ rsetbit(RCC_APB1ENR, 21); // enable GPIOB
+ rsetbit(RCC_APB2ENR, 3); // enable I2C
+ rwrite(GPIOB_CRL, 0xEE444444); // open-drain
+ rsetbitsfrom(I2C_CR2, 0, 0x2); // 2 MHz
+ rwrite(I2C_TRISE, 0x3); // MAX = 1000ns, TPCLK1 = 500ns (+1)
+ rwrite(I2C_CCR, 0x000A); // standard mode
+ rsetbit(I2C_CR1, 0); // enable
+
+}
+
+/* Reset the I2C channels and reinitialize */
+void tm1637_reset() {
+
+ rsetbit(I2C_CR1, 15); // master is busy, reset
+ rsetbit(RCC_APB1RSTR, 21); // reset I2C
+ rwrite(RCC_APB1RSTR, 0x00000000); // clear reset
+ rsetbit(RCC_APB1ENR, 21);
+ rsetbitsfrom(I2C_CR2, 0, 0x2); // 2 MHz
+ rwrite(I2C_TRISE, 0x3); // MAX = 1000ns, TPCLK1 = 500ns (+1)
+ rwrite(I2C_CCR, 0x000A); // standard mode
+ rsetbit(I2C_CR1, 0); // enable
+
+
+}
+
+/* Write value to grid, if no offset is given it writes to the first
+ * grid. Grid 1 an 2 have an additional dot that can be set */
+int set_grid(uint8_t offset, char value, bool dot) {
+
+
+ if (offset > 3) {
+ printf("Offset incorrect");
+ }
+
+ // enable dot on display if desired
+ if (dot && (offset == 1 || offset == 2)) {
+ value = value | 0x1;
+ }
+
+ int start_pos_cmd = 0x03 | (offset & 0x01) << 7 | (offset & 0x2) << 5 ;
+
+ /* Initiate writing routine */
+ start_condition();
+ rwrite(I2C_DR, WRITE_CMD);
+ if(!ack_recv())
+ return -1;
+
+ stop_condition();
+
+ if(!idle())
+ return -1;
+
+ /* Set GRID offset */
+ start_condition();
+ rwrite(I2C_DR, start_pos_cmd);
+ if(!ack_recv())
+ return -1;
+
+ stop_condition();
+
+ tm1637_reset();
+
+
+ int (*ack)() = &ack_recv;
+ if ((((value >> 4) & 0xF) == 0xF ) && !(value & 0x08)) {
+ ack = &ack10_recv;
+ }
+
+ /* Write value to segments */
+ start_condition();
+ rwrite(I2C_DR, value);
+ if(!ack()) {
+ // return -1;
+ }
+
+ stop_condition();
+ delay(); // wait for the chip to finish writing
+ tm1637_reset();
+ return 0;
}
+/* Turns on/off the led display. The degree of brightness can set [0..7]*/
+int set_display(bool on, uint8_t degree) {
+
+ int disp_cmd = 0x1; // off
+ if (on) {
+ disp_cmd = 0xF1; // TODO
+ }
+
+ start_condition();
+ rwrite(I2C_DR, disp_cmd);
+ if(!ack_recv()) {
+ printf("Can't switch on display!");
+ return -1;
+ }
+ stop_condition();
+ tm1637_reset();
+
+ return 0;
+}
+
+void tm1637_example() {
+
+ unsigned char dn[10] = {0xFC, 0x60, 0xDA, 0xF2, 0x66, 0xB6, 0xBE, 0xE0, 0xFE, 0xF6};
+ char love[4] = { 0x1C, 0xFC, 0x7C, 0x9E };
+
+ for (int i = 0; i < 4; i++) {
+ set_grid(i, love[i], NODOT);
+ }
+
+}
+
+/* HELPER ROUTINES */
+
+static void start_condition() {
+ rsetbit(I2C_CR1, 8); //start bit
+}
+
+static void stop_condition() {
+ rsetbit(I2C_CR1, 9); //stop bit
+}
+
+/* Wait for an acknowledge from the peripheral */
+int ack_recv() {
+ int cnt = 0;
+ while(!(*I2C_SR1 & 0x2)) {
+ cnt++;
+ if (cnt > TIMEOUT) {
+ printf("Error: no ack (addr bit) received \n");
+ return 0;
+ }
+ }
+ uint32_t a = *I2C_SR2; // need to read SR2 register!
+ return 1;
+
+}
+
+/* Similar, but SR2 register is not read */
+int ack10_recv() {
+ int cnt = 0;
+ while(!(*I2C_SR1 & 0x8)) {
+ cnt++;
+ if (cnt > TIMEOUT) {
+ printf("Error: no ack (addr10 bit) received \n");
+ return 0;
+ }
+ }
+ return 1;
+
+}
+
+/* Write delay chip */
+static void delay() {
+ int a = 0;
+ for (int i = 0; i < 500; i++)
+ a++;
+}
+
+
+/* Check if lines are idle (i.e. stop condition finished)*/
+int idle() {
+ int cnt = 0;
+ while(*I2C_SR2 & 0x2) {
+ cnt++;
+ if (cnt > TIMEOUT) {
+ printf("Error: busy state\n");
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
+
projects / cortex-from-scratch / blobdiff