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Added a 14 segment LED example, driven by the HT16K33 (#219)
No fritzing parts available for the device so no diagrams
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‎README.md

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[ssd1306_i2c](i2c/ssd1306_i2c) | Convert and display a bitmap on a 128x32 or 128x64 SSD1306-driven OLED display
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[pa1010d_i2c](i2c/pa1010d_i2c) | Read GPS location data, parse and display data via I2C.
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[pcf8523_i2c](i2c/pcf8523_i2c) | Read time and date values from a real time clock. Set current time and alarms on it.
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[ht16k33_i2c](i2c/ht16k33_i2c) | Drive a 4 digit 14 segment LED with an HT16K33.
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### Interpolator
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‎i2c/CMakeLists.txt

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add_subdirectory(ssd1306_i2c)
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add_subdirectory(pa1010d_i2c)
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add_subdirectory(pcf8523_i2c)
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add_subdirectory(ht16k33_i2c)
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endif ()

‎i2c/ht16k33_i2c/CMakeLists.txt

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

‎i2c/ht16k33_i2c/README.adoc

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= Attaching a 4 digit 14 segment LED driven by the HT15k33 via I2C
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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
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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
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GPIO pins are not 5v tolerant.
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NOTE: Other manufacturers make very similar devices with very similar names (e.g. Vinka VK16K33)). These may or may not work!
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== Wiring information
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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.
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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.
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Connections on Raspberry Pi Pico board, other boards may vary.
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GPIO 4 (pin 6)-> SDA on LED board
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GPIO 5 (pin 7)-> SCL on LED board
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GND (pin 38) -> GND on LED board
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5v (pin 40) -> VCC on LED board
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3.3v (pin 36) -> vi2c on LED board
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== List of Files
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CMakeLists.txt:: CMake file to incorporate the example in to the examples build tree.
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ht15k33_i2c.c:: The example code.
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== Bill of Materials
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.A list of materials required for the example
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[[ht15k33_i2c-bom-table]]
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[cols=3]
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|===
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| *Item* | *Quantity* | Details
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| Breadboard | 1 | generic part
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| Raspberry Pi Pico | 1 | https://www.raspberrypi.com/products/raspberry-pi-pico/
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| ht16k33 based LCD panel | 1 | generic part
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| M/M Jumper wires | 5 | generic part
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|===

‎i2c/ht16k33_i2c/ht16k33_i2c.c

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

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