82 lines
2.9 KiB
C
82 lines
2.9 KiB
C
#include "shared-bindings/dotclockframebuffer/__init__.h"
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#include <stdint.h>
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#include <stdbool.h>
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#include <stddef.h>
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#define DELAY (0x80)
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static void pin_change(dotclockframebuffer_ioexpander_spi_bus *bus, uint32_t set_bits, uint32_t clear_bits) {
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uint32_t data = (bus->addr_reg_shadow.u32 & ~clear_bits) | set_bits;
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// no way to signal failure to caller!
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(void)common_hal_busio_i2c_write(bus->bus, bus->i2c_device_address, (uint8_t *)&data, bus->i2c_write_size);
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bus->addr_reg_shadow.u32 = data;
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}
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static void ioexpander_bus_send(dotclockframebuffer_ioexpander_spi_bus *bus,
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bool is_command,
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const uint8_t *data, uint32_t data_length) {
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int dc_mask = is_command ? 0 : 0x100;
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for (uint32_t i = 0; i < data_length; i++) {
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int bits = data[i] | dc_mask;
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for (uint32_t j = 0; j < 9; j++) {
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// CPOL=CPHA=0: output fresh data on falling edge of clk or cs
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if (bits & 0x100) {
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pin_change(bus, /* set */ bus->mosi_mask, /* clear */ bus->clk_mask | bus->cs_mask);
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} else {
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pin_change(bus, /* set */ 0, /* clear */ bus->mosi_mask | bus->clk_mask | bus->cs_mask);
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}
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// Display latches bit on rising edge of CLK
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pin_change(bus, /* set */ bus->clk_mask, /* clear */ 0);
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// next bit
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bits <<= 1;
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}
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}
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}
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// Send a circuitpython-style display initialization sequence over an i2c-attached bus expander
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// This always assumes
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// * 9-bit SPI (no DC pin)
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// * CPOL=CPHA=0
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// * CS deasserted after each init sequence step, but not otherwise just like
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// displayio fourwire bus without data_as_commands
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void dotclockframebuffer_ioexpander_send_init_sequence(dotclockframebuffer_ioexpander_spi_bus *bus, const uint8_t *init_sequence, uint16_t init_sequence_len) {
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while (!common_hal_busio_i2c_try_lock(bus->bus)) {
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RUN_BACKGROUND_TASKS;
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}
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// ensure deasserted CS and idle CLK
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pin_change(bus, /* set */ bus->cs_mask, /* clear */ bus->clk_mask);
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for (uint32_t i = 0; i < init_sequence_len; /* NO INCREMENT */) {
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const uint8_t *cmd = init_sequence + i;
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uint8_t data_size = *(cmd + 1);
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bool delay = (data_size & DELAY) != 0;
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data_size &= ~DELAY;
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const uint8_t *data = cmd + 2;
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ioexpander_bus_send(bus, true, cmd, 1);
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ioexpander_bus_send(bus, false, data, data_size);
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// idle CLK
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pin_change(bus, 0, /* clear */ bus->clk_mask);
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// deassert CS
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pin_change(bus, /* set */ bus->cs_mask, 0);
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uint16_t delay_length_ms = 10;
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if (delay) {
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data_size++;
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delay_length_ms = *(cmd + 1 + data_size);
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if (delay_length_ms == 255) {
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delay_length_ms = 500;
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}
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}
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mp_hal_delay_ms(delay_length_ms);
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i += 2 + data_size;
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}
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common_hal_busio_i2c_unlock(bus->bus);
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}
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