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drivers: auxdisplay: hd44780: add rs-line-delay dt parameter

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In order for the driver to be compliant with the timing sequence
diagrams presented in the reference manual, the MCU has to wait
for some additional period of time while setting both the rs and rw
lines.

Signed-off-by: Jan Kuliga <jtkuliga@gmail.com>
This commit is contained in:
Jan Kuliga 2024-09-01 17:17:30 +02:00 committed by Benjamin Cabé
parent 55de1c9719
commit 91a14dcc50
2 changed files with 10 additions and 0 deletions
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3
drivers/auxdisplay/auxdisplay_hd44780.c
View file

@ -70,6 +70,7 @@ struct auxdisplay_hd44780_config {
uint8_t line_addresses[4]; uint8_t line_addresses[4];
uint16_t enable_line_rise_delay; uint16_t enable_line_rise_delay;
uint16_t enable_line_fall_delay; uint16_t enable_line_fall_delay;
uint16_t rs_line_delay;
uint16_t clear_delay; uint16_t clear_delay;
uint16_t boot_delay; uint16_t boot_delay;
}; };
@ -96,6 +97,7 @@ static void auxdisplay_hd44780_command(const struct device *dev, bool rs, uint8_
int8_t ncommands = (mode == AUXDISPLAY_HD44780_MODE_4_BIT) ? 2 : 1; int8_t ncommands = (mode == AUXDISPLAY_HD44780_MODE_4_BIT) ? 2 : 1;
gpio_pin_set_dt(&config->rs_gpio, rs); gpio_pin_set_dt(&config->rs_gpio, rs);
k_sleep(K_NSEC(config->rs_line_delay));
while (ncommands--) { while (ncommands--) {
for (int8_t line = 7; line >= lsb_line; --line) { for (int8_t line = 7; line >= lsb_line; --line) {
@ -569,6 +571,7 @@ static const struct auxdisplay_driver_api auxdisplay_hd44780_auxdisplay_api = {
.backlight_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, backlight_gpios, {0}), \ .backlight_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, backlight_gpios, {0}), \
.enable_line_rise_delay = DT_INST_PROP(inst, enable_line_rise_delay_ns), \ .enable_line_rise_delay = DT_INST_PROP(inst, enable_line_rise_delay_ns), \
.enable_line_fall_delay = DT_INST_PROP(inst, enable_line_fall_delay_ns), \ .enable_line_fall_delay = DT_INST_PROP(inst, enable_line_fall_delay_ns), \
.rs_line_delay = DT_INST_PROP(inst, rs_line_delay_ns), \
.clear_delay = DT_INST_PROP(inst, clear_command_delay_us), \ .clear_delay = DT_INST_PROP(inst, clear_command_delay_us), \
.boot_delay = DT_INST_PROP(inst, boot_delay_ms), \ .boot_delay = DT_INST_PROP(inst, boot_delay_ms), \
}; \ }; \

7
dts/bindings/auxdisplay/hit,hd44780.yaml
View file

@ -70,6 +70,13 @@ properties:
Delay time (in ns) to wait after enable line falls before sending Delay time (in ns) to wait after enable line falls before sending
another command. Default is as per Hitachi HD44780 specification. another command. Default is as per Hitachi HD44780 specification.
rs-line-delay-ns:
type: int
default: 60
description: |
Delay time (in ns) to wait after rs/rw line state has been set up before
sending another command. Default is as per Hitachi HD44780 specification.
clear-command-delay-us: clear-command-delay-us:
type: int type: int
default: 5000 default: 5000