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can now control daisy-chained MAX7219 displays

This commit is contained in:
King Kévin 2017-04-01 17:18:51 +02:00
parent 0dbf02ca3c
commit d14860aab5
2 changed files with 42 additions and 34 deletions
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57
lib/led_max7219.c
View File

@ -158,13 +158,16 @@ static const uint8_t ascii_7segments[] = {
/** write data on SPI bus and handle load signal
* @param[in] data bytes to write
*/
static void led_max7219_write(uint16_t data)
static void led_max7219_write(uint16_t data, uint8_t display)
{
gpio_clear(GPIO(LED_MAX7219_LOAD_PORT), GPIO(LED_MAX7219_LOAD_PIN)); // ensure load pin is low (data is put in MAX7219 register on rising edge)
while (SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_BSY); // wait until not busy
spi_send(SPI(LED_MAX7219_SPI), data); // send data
while (!(SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_TXE)); // wait until Tx is empty (reference manual says BSY should also cover this, but it doesn't)
while (SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_BSY); // wait until not busy (= transmission completed)
for (uint16_t i=0; i<=display; i++) { // go though all displays
while (SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_BSY); // wait until not busy
spi_send(SPI(LED_MAX7219_SPI), data); // send data
while (!(SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_TXE)); // wait until Tx is empty (reference manual says BSY should also cover this, but it doesn't)
while (SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_BSY); // wait until not busy (= transmission completed)
data = 0x0000; // send no-op command to shift initial command to correct display
}
gpio_set(GPIO(LED_MAX7219_LOAD_PORT), GPIO(LED_MAX7219_LOAD_PIN)); // create rising edge on load pin for data to be set in MAX7219 register
}
@ -186,65 +189,63 @@ void led_max7219_setup(void)
spi_init_master(SPI(LED_MAX7219_SPI), SPI_CR1_BAUDRATE_FPCLK_DIV_8, SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE, SPI_CR1_CPHA_CLK_TRANSITION_1, SPI_CR1_DFF_16BIT, SPI_CR1_MSBFIRST); // initialise SPI as master, divide clock by 8 since max MAX7219 clock is 10 MHz and max SPI PCLK clock is 72 Mhz, depending on which SPI is used, set clock polarity to idle low (as in the datasheet of the MAX7219, but not that important), set clock phase to go high when bit is set (depends on polarity) as data is stored on MAX7219 on rising edge), use 16 bits frames (as used by MAX7219), use MSB first
spi_set_unidirectional_mode(SPI(LED_MAX7219_SPI)); // we only need to transmit data
spi_enable(SPI(LED_MAX7219_SPI)); // enable SPI
// default setting
led_max7219_off(); // switch display off
led_max7219_test(false); // disable test mode
led_max7219_intensity(15); // set maximum intensity
led_max7219_write(0x0B07); // set scan limit to display all 7 digits
}
void led_max7219_on(void)
void led_max7219_on(uint8_t display)
{
led_max7219_write(0x0C01); // set scan limit to display all 7 digits
led_max7219_write(0x0C01, display); // put in normal operation more (registers remain as set)
}
void led_max7219_off(void)
void led_max7219_off(uint8_t display)
{
led_max7219_write(0x0C00); // put in shutdown mode (registers remain as set)
led_max7219_write(0x0C00, display); // put in shutdown mode (registers remain as set)
}
void led_max7219_test(bool test)
void led_max7219_test(bool test, uint8_t display)
{
if (test) {
led_max7219_write(0x0F01); // go into display test mode
led_max7219_write(0x0F01, display); // go into display test mode
} else {
led_max7219_write(0x0F00); // go into normal operation mode
led_max7219_write(0x0F00, display); // go into normal operation mode
}
}
void led_max7219_intensity(uint8_t intensity)
void led_max7219_intensity(uint8_t intensity, uint8_t digits, uint8_t display)
{
if (intensity>15) { // intensity must be 0-15 (corresponds to (2*brightness+1)/32)
return;
}
led_max7219_write(0x0A00+intensity); // set brightness
if (digits<1 || digits>8) { // scan limit must bit 0-7
return;
}
led_max7219_write(0x0A00+intensity, display); // set brightness
led_max7219_write(0x0B00+digits-1, display); // set scan limit to display digits
}
bool led_max7219_text(char* text)
bool led_max7219_text(char* text, uint8_t display)
{
for (uint8_t i=0; i<8; i++) { // input text should only contain printable character (8th bit is used for dots)
if ((text[i]&0x7f)<' ' || (text[i]&0x7f)>=' '+LENGTH(ascii_7segments)) {
return false;
}
}
led_max7219_write(0x0900); // disable BCD decoding on all 7 digits
led_max7219_write(0x0900, display); // disable BCD decoding on all 7 digits
for (uint8_t i=0; i<8; i++) { // display text
led_max7219_write(((i+1)<<8)+(ascii_7segments[(text[7-i]&0x7f)-' '])+(text[7-i]&0x80)); // send digit (in reverse order)
led_max7219_write(((i+1)<<8)+(ascii_7segments[(text[7-i]&0x7f)-' '])+(text[7-i]&0x80), display); // send digit (in reverse order)
}
return true;
}
void led_max7219_number(uint32_t number, uint8_t dots)
void led_max7219_number(uint32_t number, uint8_t dots, uint8_t display)
{
led_max7219_write(0x09FF); // enable BCD decoding on all 7 digits
led_max7219_write(0x09FF, display); // enable BCD decoding on all 7 digits
for (uint8_t digit=0; digit<8; digit++) { // go through digits
if (0==digit) { // display 0 on 0 only to first digit
led_max7219_write(((digit+1)<<8) + (number%10) + (((dots>>digit)&0x01)<<7)); // display digit
led_max7219_write(((digit+1)<<8) + (number%10) + (((dots>>digit)&0x01)<<7), display); // display digit
} else if (0==number) { // display blank on other digits
led_max7219_write(((digit+1)<<8) + 0x0F + (((dots>>digit)&0x01)<<7)); // display blank
led_max7219_write(((digit+1)<<8) + 0x0F + (((dots>>digit)&0x01)<<7), display); // display blank
} else {
led_max7219_write(((digit+1)<<8) + (number%10) + (((dots>>digit)&0x01)<<7)); // display digit
led_max7219_write(((digit+1)<<8) + (number%10) + (((dots>>digit)&0x01)<<7), display); // display digit
}
number /= 10; // get next digit
}

19
lib/led_max7219.h
View File

@ -25,27 +25,34 @@
*/
void led_max7219_setup(void);
/** switch display on
* @param[in] display display number in chain
*/
void led_max7219_on(void);
void led_max7219_on(uint8_t display);
/** switch display off
* @param[in] display display number in chain
*/
void led_max7219_off(void);
void led_max7219_off(uint8_t display);
/** switch display in test or normal operation mode
* @param[in] test switch in test mode (else normal operation)
* @param[in] display display number in chain
*/
void led_max7219_test(bool test);
void led_max7219_test(bool test, uint8_t display);
/** set display intensity
* @param[in] intensity level to set (0-15)
* @param[in] digits number of digits to display (1-8)
* @param[in] display display number in chain
*/
void led_max7219_intensity(uint8_t intensity);
void led_max7219_intensity(uint8_t intensity, uint8_t digits, uint8_t display);
/** display text
* @param[in] text text to display (8 characters)
* @param[in] display display number in chain
* @note use first bit of each character to enable dot
* @return false if string has unsupported characters
*/
bool led_max7219_text(char* text);
bool led_max7219_text(char* text, uint8_t display);
/** display number
* @param[in] number number to display (8 digits max)
* @param[in] dots set bit if dot on corresponding digit should be displayed
* @param[in] display display number in chain
*/
void led_max7219_number(uint32_t number, uint8_t dots);
void led_max7219_number(uint32_t number, uint8_t dots, uint8_t display);