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Added a 14 segment LED example, driven by the HT16K33 (#219)

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No fritzing parts available for the device so no diagrams
This commit is contained in:
James Hughes
2022-11-25 17:32:13 +00:00
committed by GitHub
parent aa9a72b494
commit 82eae4c8ea
5 changed files with 281 additions and 0 deletions
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i2c/CMakeLists.txt
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@@ -10,4 +10,5 @@ if (NOT PICO_NO_HARDWARE)
add_subdirectory(ssd1306_i2c)
add_subdirectory(pa1010d_i2c)
add_subdirectory(pcf8523_i2c)
add_subdirectory(ht16k33_i2c)
endif ()

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i2c/ht16k33_i2c/CMakeLists.txt Normal file
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add_executable(ht16k33_i2c
ht16k33_i2c.c
)
# pull in common dependencies and additional i2c hardware support
target_link_libraries(ht16k33_i2c pico_stdlib hardware_i2c)
# create map/bin/hex file etc.
pico_add_extra_outputs(ht16k33_i2c)
# add url via pico_set_program_url
example_auto_set_url(ht16k33_i2c)

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i2c/ht16k33_i2c/README.adoc Normal file
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= Attaching a 4 digit 14 segment LED driven by the HT15k33 via I2C
This example code shows how to interface the Raspberry Pi Pico to one HT16K33 driven 4 digit 14 segment LED. The device used for development
uses VCC at 5v, but also allows the I2C voltage to be selected by connecting the vi2c pin to the appropriate voltage, in the Pico case 3v3 as the
GPIO pins are not 5v tolerant.
NOTE: Other manufacturers make very similar devices with very similar names (e.g. Vinka VK16K33)). These may or may not work!
== Wiring information
Wiring up the device requires 5 jumpers, to connect VCC (3.3v), GND, vi2c (3v3), SDA and SCL. The example here uses I2C port 0, which is assigned to GPIO 4 (SDA) and 5 (SCL) in software. Power is supplied from the 3.3V pin.
WARNING: Some displays of this type are 5v with no option to select 3v3 for the I2c. If you wish to use a 5v display you will need to use level shifters on the SDA and SCL lines to convert from the 3.3V used by the RP2040.
Connections on Raspberry Pi Pico board, other boards may vary.
GPIO 4 (pin 6)-> SDA on LED board
GPIO 5 (pin 7)-> SCL on LED board
GND (pin 38) -> GND on LED board
5v (pin 40) -> VCC on LED board
3.3v (pin 36) -> vi2c on LED board
== List of Files
CMakeLists.txt:: CMake file to incorporate the example in to the examples build tree.
ht15k33_i2c.c:: The example code.
== Bill of Materials
.A list of materials required for the example
[[ht15k33_i2c-bom-table]]
[cols=3]
|===
| *Item* | *Quantity* | Details
| Breadboard | 1 | generic part
| Raspberry Pi Pico | 1 | https://www.raspberrypi.com/products/raspberry-pi-pico/
| ht16k33 based LCD panel | 1 | generic part
| M/M Jumper wires | 5 | generic part
|===

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i2c/ht16k33_i2c/ht16k33_i2c.c Normal file
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/**
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <stdio.h>
#include <string.h>
#include "pico/stdlib.h"
#include "hardware/i2c.h"
#include "pico/binary_info.h"
#include <ctype.h>
/* Example code to drive a 4 digit 14 segment LED backpack using a HT16K33 I2C
driver chip
NOTE: The panel must be capable of being driven at 3.3v NOT 5v. The Pico
GPIO (and therefore I2C) cannot be used at 5v. In development the particular
device used allowed the PCB VCC to be 5v, but you can set the I2C voltage
to 3.3v.
Connections on Raspberry Pi Pico board, other boards may vary.
GPIO 4 (pin 6)-> SDA on LED board
GPIO 5 (pin 7)-> SCL on LED board
GND (pin 38) -> GND on LED board
5v (pin 40) -> VCC on LED board
3.3v (pin 36) -> vi2c on LED board
*/
// How many digits are on our display.
#define NUM_DIGITS 4
// By default these display drivers are on bus address 0x70. Often there are
// solder on options on the PCB of the backpack to set an address between
// 0x70 and 0x77 to allow multiple devices to be used.
const int I2C_addr = 0x70;
// commands
#define HT16K33_SYSTEM_STANDBY 0x20
#define HT16K33_SYSTEM_RUN 0x21
#define HT16K33_SET_ROW_INT 0xA0
#define HT16K33_BRIGHTNESS 0xE0
// Display on/off/blink
#define HT16K33_DISPLAY_SETUP 0x80
// OR/clear these to display setup register
#define HT16K33_DISPLAY_OFF 0x0
#define HT16K33_DISPLAY_ON 0x1
#define HT16K33_BLINK_2HZ 0x2
#define HT16K33_BLINK_1HZ 0x4
#define HT16K33_BLINK_0p5HZ 0x6
// Converts a character to the bit pattern needed to display the right segments.
// These are pretty standard for 14segment LED's
uint16_t char_to_pattern(char ch) {
// Map, "A" to "Z"
int16_t alpha[] = {
0xF7,0x128F,0x39,0x120F,0xF9,0xF1,0xBD,0xF6,0x1209,0x1E,0x2470,0x38,0x536,0x2136,
0x3F,0xF3,0x203F,0x20F3,0x18D,0x1201,0x3E,0xC30,0x2836,0x2D00,0x1500,0xC09
};
// Map, "0" to "9"
int16_t num[] = {
0xC3F,0x406,0xDB,0x8F,0xE6,0xED,0xFD,0x1401,0xFF,0xE7
};
if (isalpha(ch))
return alpha[toupper(ch) - 'A'];
if (isdigit(ch))
return num[ch - '0'];
return 0;
}
/* Quick helper function for single byte transfers */
inline void i2c_write_byte(uint8_t val) {
#ifdef i2c_default
i2c_write_blocking(i2c_default, I2C_addr, &val, 1, false);
#endif
}
void ht16k33_init() {
i2c_write_byte(HT16K33_SYSTEM_RUN);
i2c_write_byte(HT16K33_SET_ROW_INT);
i2c_write_byte(HT16K33_DISPLAY_SETUP | HT16K33_DISPLAY_ON);
}
// Send a specific binary value to the specified digit
inline void ht16k33_display_set(int position, uint16_t bin) {
uint8_t buf[3];
buf[0] = position * 2;
buf[1] = bin & 0xff;
buf[2] = bin >> 8;
i2c_write_blocking(i2c_default, I2C_addr, buf, count_of(buf), false);
}
inline void ht16k33_display_char(int position, char ch) {
ht16k33_display_set(position, char_to_pattern(ch));
}
void ht16k33_display_string(char *str) {
int digit = 0;
while (*str && digit <= NUM_DIGITS) {
ht16k33_display_char(digit++, *str++);
}
}
void ht16k33_scroll_string(char *str, int interval_ms) {
int l = strlen(str);
if (l <= NUM_DIGITS) {
ht16k33_display_string(str);
}
else {
for (int i = 0; i < l - NUM_DIGITS + 1; i++) {
ht16k33_display_string(&str[i]);
sleep_ms(interval_ms);
}
}
}
void ht16k33_set_brightness(int bright) {
i2c_write_byte(HT16K33_BRIGHTNESS | (bright <= 15 ? bright : 15));
}
void ht16k33_set_blink(int blink) {
int s = 0;
switch (blink) {
default: break;
case 1: s = HT16K33_BLINK_2HZ; break;
case 2: s = HT16K33_BLINK_1HZ; break;
case 3: s = HT16K33_BLINK_0p5HZ; break;
}
i2c_write_byte(HT16K33_DISPLAY_SETUP | HT16K33_DISPLAY_ON | s);
}
int main() {
stdio_init_all();
#if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN)
#warning i2c/ht16k33_i2c example requires a board with I2C pins
#else
// This example will use I2C0 on the default SDA and SCL pins (4, 5 on a Pico)
i2c_init(i2c_default, 100 * 1000);
gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
// Make the I2C pins available to picotool
bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C));
printf("Welcome to HT33k16!\n");
ht16k33_init();
ht16k33_display_set(0, 0);
ht16k33_display_set(1, 0);
ht16k33_display_set(2, 0);
ht16k33_display_set(3, 0);
again:
ht16k33_scroll_string("Welcome to the Raspberry Pi Pico", 150);
// Do a speeding up propeller effort using the inner segments
int bits[] = {0x40, 0x0100, 0x0200, 0x0400, 0x80, 0x2000, 0x1000, 0x0800};
for (int j = 0;j < 10;j++) {
for (int i = 0;i< count_of(bits); i++) {
for (int digit = 0;digit <= NUM_DIGITS; digit++) {
ht16k33_display_set(digit, bits[i]);
}
sleep_ms(155 - j*15);
}
}
char *strs[] = {
"Help", "I am", "in a", "Pico", "and ", "Cant", "get ", "out "
};
for (int i = 0; i < count_of(strs); i++) {
ht16k33_display_string(strs[i]);
sleep_ms(500);
}
sleep_ms(1000);
// Test brightness and blinking
// Set all segments on all digits on
ht16k33_display_set(0, 0xffff);
ht16k33_display_set(1, 0xffff);
ht16k33_display_set(2, 0xffff);
ht16k33_display_set(3, 0xffff);
// Fade up and down
for (int j=0;j<5;j++) {
for (int i = 0; i < 15; i++) {
ht16k33_set_brightness(i);
sleep_ms(30);
}
for (int i = 14; i >=0; i--) {
ht16k33_set_brightness(i);
sleep_ms(30);
}
}
ht16k33_set_brightness(15);
ht16k33_set_blink(1); // 0 for no blink, 1 for 2Hz, 2 for 1Hz, 3 for 0.5Hz
sleep_ms(5000);
ht16k33_set_blink(0);
goto again;
return 0;
#endif
}