+/*** Emulated TM1618 LED Driver ***/
+
+/*
+ * Theory of operation:
+ *
+ * TM1618 communicates using a bi-directional SPI-like protocol.
+ * The AC unit is sending a stream of commands like this once per ca. 4 ms:
+ *
+ * 00 - set mode: 4 grids, 8 segments
+ * 44 - will write to display memory, no auto-increment
+ * Cx - set memory address to x
+ * yy - data to write, two most-significant bits are always zero
+ * 8B - display ON, duty cycle 10/16
+ *
+ * No read commands are issued, so we can simulate TM1618 using a pure SPI slave.
+ *
+ * Commands are delimited using the STB* (strobe) pin, but since our opto-couplers
+ * are negating, we cannot route this pin to SS (slave select) of our SPI.
+ * We tried triggering an external interrupt by this pin, but it turned out
+ * that the latency is too high.
+ *
+ * Instead, we ignore STB* completely and implement a self-synchronizing receiver:
+ *
+ * - The only byte which can have top 2 bits both set is the Cx command,
+ * so we can use this to find memory addresses and data in the stream.
+ * We can ignore all other commands.
+ *
+ * - Whenever 1 ms passes since the last byte was received, we reset the SPI.
+ * This allows us to recover from misaligned bytes.
+ */
+
+static void tm_init(void)
+{
+ // Configure SPI2 to receive
+ spi_set_receive_only_mode(SPI2);
+ spi_enable_software_slave_management(SPI2);
+ spi_set_nss_low(SPI2);
+ spi_send_lsb_first(SPI2);
+ spi_set_clock_polarity_0(SPI2);
+ spi_set_clock_phase_1(SPI2);
+ spi_enable_rx_buffer_not_empty_interrupt(SPI2);
+ nvic_enable_irq(NVIC_SPI2_IRQ);
+ spi_enable(SPI2);
+
+ // TIM3 will handle receive timeout
+ timer_set_prescaler(TIM3, CPU_CLOCK_MHZ-1); // 1 tick = 1 μs
+ timer_set_mode(TIM3, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_DOWN);
+ timer_update_on_overflow(TIM3);
+ timer_disable_preload(TIM3);
+ timer_one_shot_mode(TIM3);
+ timer_enable_irq(TIM3, TIM_DIER_UIE);
+ nvic_enable_irq(NVIC_TIM3_IRQ);
+}
+
+/*
+ * Data memory of TM1618:
+ *
+ * [0] . . . - - - - -
+ * [1] . . - - HEAT . . .
+ * [2] . . . DRY - SLP MED LOW
+ * [3] . . HIGH AUTO COOL . . .
+ * [4] . . . B2 - G2 D2 C2
+ * [5] . . E2 F2 A2 . . .
+ * [6] . . . B1 - G1 D1 C1
+ * [7] . . E1 F1 A1 . . .
+ *
+ * "." is an always-zero bit not defined by TM1618, "-" is defined, but not used by AC.
+ */
+static volatile byte tm_data[8];
+static volatile uint tm_overruns;
+
+static volatile byte tm_buffer[256];
+static volatile uint tm_len;
+
+/*
+ *
+ * Display segments:
+ *
+ * +--A--+
+ * | |
+ * F B
+ * | |
+ * +--G--+
+ * | |
+ * E C
+ * | |
+ * +--D--+
+ */
+
+enum tm_seg {
+ SEGa = 0x0800,
+ SEGb = 0x0010,
+ SEGc = 0x0001,
+ SEGd = 0x0002,
+ SEGe = 0x2000,
+ SEGf = 0x1000,
+ SEGg = 0x0004,
+};
+
+static const u16 tm_digits[10] = {
+ [0] = SEGa | SEGb | SEGc | SEGd | SEGe | SEGf,
+ [1] = SEGb | SEGc,
+ [2] = SEGa | SEGb | SEGd | SEGe | SEGg,
+ [3] = SEGa | SEGb | SEGc | SEGd | SEGg,
+ [4] = SEGb | SEGc | SEGf | SEGg,
+ [5] = SEGa | SEGc | SEGd | SEGf | SEGg,
+ [6] = SEGa | SEGc | SEGd | SEGe | SEGf | SEGg,
+ [7] = SEGa | SEGb | SEGc,
+ [8] = SEGa | SEGb | SEGc | SEGd | SEGe | SEGf | SEGg,
+ [9] = SEGa | SEGb | SEGc | SEGd | SEGf | SEGg,
+};
+
+static volatile uint tm_timeouts;
+
+void spi2_isr(void)
+{
+ if (SPI_SR(SPI2) & SPI_SR_OVR)
+ tm_overruns++;
+ if (SPI_SR(SPI2) & SPI_SR_RXNE) {
+ byte x = SPI_DR(SPI2) ^ 0xff;
+#if 0
+ if (tm_len < ARRAY_SIZE(tm_buffer))
+ tm_buffer[tm_len++] = x;
+#endif
+ static byte tm_address;
+ if (tm_address) {
+ tm_data[tm_address & 7] = x;
+ tm_address = 0;
+ } else if ((x & 0xc0) == 0xc0) {
+ tm_address = x;
+ }
+ timer_set_period(TIM3, 999);
+ timer_generate_event(TIM3, TIM_EGR_UG);
+ timer_enable_counter(TIM3);
+ }
+}
+
+void tim3_isr(void)
+{
+ if (TIM_SR(TIM3) & TIM_SR_UIF) {
+ TIM_SR(TIM3) &= ~TIM_SR_UIF;
+ tm_timeouts++;
+ spi_set_nss_high(SPI2);
+ spi_set_nss_low(SPI2);
+ }
+}
+
+static void tm_show(void)
+{
+ debug_printf("TM:");
+ for (uint i=0; i<8; i++)
+ debug_printf(" %02x", tm_data[i]);
+ debug_printf(" o=%d t=%d", tm_overruns, tm_timeouts);
+
+ debug_printf(" =>");
+ if (tm_data[1] & 0x08)
+ debug_printf(" HEAT");
+ if (tm_data[2] & 0x10)
+ debug_printf(" DRY");
+ if (tm_data[2] & 0x04)
+ debug_printf(" SLEEP");
+ if (tm_data[2] & 0x02)
+ debug_printf(" MED");
+ if (tm_data[2] & 0x01)
+ debug_printf(" LOW");
+ if (tm_data[3] & 0x20)
+ debug_printf(" HIGH");
+ if (tm_data[3] & 0x10)
+ debug_printf(" AUTO");
+ if (tm_data[3] & 0x08)
+ debug_printf(" COOL");
+
+ debug_putc(' ');
+ for (int i=0; i<2; i++) {
+ uint x = (tm_data[7-2*i] << 8) | tm_data[6-2*i];
+ uint j = 0;
+ while (j < 10 && tm_digits[j] != x)
+ j++;
+ if (j == 10)
+ debug_putc('?');
+ else
+ debug_putc('0' + j);
+ }
+
+ debug_putc('\n');
+
+#if 0
+ static byte tm_dumped;
+ if (!tm_dumped && tm_len == ARRAY_SIZE(tm_buffer)) {
+ for (uint i=0; i < tm_len; i++)
+ debug_printf("%02x ", tm_buffer[i]);
+ debug_putc('\n');
+ // tm_dumped = 1;
+ tm_len = 0;
+ }
+#endif
+}
+
+/*** Infra-red remote control simulator ***/
+
+/*
+ * The AC unit expects demodulated IR signal. The RC sends 52-bit messages
+ * (plus leader and trailer). The last 4 bits are a complement of checksum
+ * of 4-bit nibbles.
+ *
+ * We represent the messages as two 32-bit words, the upper word containing
+ */
+
+#define RC_POWER_OFF_HI 0b00000000000000000000
+#define RC_POWER_OFF_LO 0b00000000000000010000000010100100
+
+#define RC_DEFAULT_HI 0b00000011000000000000
+
+// Cooling with different fan settings. Combines with a temperature setting (17-30).
+#define RC_COOL_AUTO 0b00000000000000010000000000000000
+#define RC_COOL_HIGH 0b00000000000000010000100000000000
+#define RC_COOL_MED 0b00000000000000010001000100000000
+#define RC_COOL_LOW 0b00000000000000010010001000000000
+
+static const u32 rc_cool_fan[4] = {
+ RC_COOL_AUTO,
+ RC_COOL_LOW,
+ RC_COOL_MED,
+ RC_COOL_HIGH,
+};
+
+// Heating with fixed fan setting. Combines with a temperature setting (15-25).
+#define RC_WARM 0b00000000000000010000001100000000
+
+// Dehumidifying with fixed fan setting. This is always sent with temperature=17.
+#define RC_DEHUMIDIFY 0b00000000000000010010010000000000
+
+// This can be added to any command to enable sleep mode, but we do not issue it yet.
+#define RC_SLEEP 0b00000000000010000000000000000000
+
+enum rc_mode {
+ MODE_OFF,
+ MODE_COOL,
+ MODE_WARM,
+ MODE_DEHUMIDIFY,
+};
+
+static byte rc_mode = MODE_COOL; // MODE_xxx
+static byte rc_fan; // 0-3
+static byte rc_temp = 17; // 15-30
+
+static void rc_init(void)
+{
+ // TIM4 runs at 1 MHz and it is used for timing of RC pulses
+ timer_set_prescaler(TIM4, CPU_CLOCK_MHZ - 1);
+ timer_set_mode(TIM4, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
+ timer_update_on_overflow(TIM4);
+ timer_disable_preload(TIM4);
+ timer_one_shot_mode(TIM4);
+ timer_enable_irq(TIM4, TIM_DIER_UIE);
+ nvic_enable_irq(NVIC_TIM4_IRQ);
+}
+
+static u32 rc_pattern[2];
+static uint rc_tick;
+
+static void rc_encode(void)
+{
+ if (rc_mode == MODE_OFF) {
+ rc_pattern[0] = RC_POWER_OFF_HI;
+ rc_pattern[1] = RC_POWER_OFF_LO;
+ return;
+ }
+
+ rc_pattern[0] = RC_DEFAULT_HI;
+ uint t = rc_temp;
+
+ if (rc_mode == MODE_COOL) {
+ rc_pattern[1] = rc_cool_fan[rc_fan];
+ if (t < 17)
+ t = 17;
+ if (t > 30)
+ t = 30;
+ } else if (rc_mode == MODE_WARM) {
+ rc_pattern[1] = RC_WARM;
+ if (t < 15)
+ t = 15;
+ if (t > 25)
+ t = 25;
+ } else {
+ rc_pattern[1] = RC_DEHUMIDIFY;
+ t = 17;
+ }
+
+ // Encode temperature
+ rc_pattern[1] |= (t - 15) << 4;
+
+ // Compute checksum
+ uint sum = 0;
+ for (uint i=0; i<2; i++)
+ for (uint j=0; j<32; j+=4)
+ sum += (rc_pattern[i] >> j) & 0x0f;
+ rc_pattern[1] |= (sum & 0x0f) ^ 0x0f;
+}
+
+void tim4_isr(void)
+{
+ if (TIM_SR(TIM4) & TIM_SR_UIF) {
+ TIM_SR(TIM4) &= ~TIM_SR_UIF;
+
+ bool val; // 1=pulse, 0=break
+ uint duration; // in μs
+
+ switch (rc_tick) {
+ case 0:
+ // Better be safe
+ return;
+ case 2:
+ case 108:
+ // Initial / final marker
+ val = 0;
+ duration = 3600;
+ // debug_putc('#');
+ break;
+ case 110:
+ // Inter-packet gap
+ val = 0;
+ duration = 10000;
+ // debug_putc('$');
+ break;
+ case 111:
+ // End of message
+ rc_tick = 0;
+ return;
+ default:
+ if (rc_tick % 2) {
+ val = 1;
+ duration = 565;
+ // debug_putc('*');
+ } else {
+ // Even ticks 4 to 106 transmit 52 bits of data
+ uint i = 12 + (rc_tick - 4) / 2;
+ val = 0;
+ if (rc_pattern[i>>5] & (0x80000000 >> (i & 31))) {
+ duration = 1471;
+ // debug_putc('B');
+ } else {
+ duration = 480;
+ // debug_putc('A');
+ }
+ }
+ }
+
+ rc_tick++;
+
+ if (val)
+ gpio_set(GPIOA, GPIO8);
+ else
+ gpio_clear(GPIOA, GPIO8);
+
+ timer_set_period(TIM4, duration - 1);
+ timer_generate_event(TIM4, TIM_EGR_UG);
+ timer_enable_counter(TIM4);
+ }
+}
+
+static void rc_send(void)
+{
+ if (rc_tick)
+ return;
+
+ rc_encode();
+ debug_printf("RC sending: %05x %08x (mode=%d, fan=%d, temp=%d)\n",
+ (uint) rc_pattern[0], (uint) rc_pattern[1],
+ rc_mode, rc_fan, rc_temp);
+ rc_tick = 1;
+
+ timer_set_period(TIM4, 1);
+ timer_generate_event(TIM4, TIM_EGR_UG);
+ timer_enable_counter(TIM4);
+}
+
+static bool rc_key(char key)
+{
+ if (key == 'o') {
+ rc_mode = MODE_OFF;
+ rc_send();
+ return true;
+ } else if (key == 'c') {
+ rc_mode = MODE_COOL;
+ rc_send();
+ return true;
+ } else if (key == 'w') {
+ rc_mode = MODE_WARM;
+ rc_send();
+ return true;
+ } else if (key == 'd') {
+ rc_mode = MODE_DEHUMIDIFY;
+ rc_send();
+ return true;
+ } else if (key == 'a') {
+ rc_fan = 0;
+ rc_send();
+ return true;
+ } else if (key == 'l') {
+ rc_fan = 1;
+ rc_send();
+ return true;
+ } else if (key == 'm') {
+ rc_fan = 2;
+ rc_send();
+ return true;
+ } else if (key == 'h') {
+ rc_fan = 3;
+ rc_send();
+ return true;
+ } else if (key >= '7' && key <= '9') {
+ rc_temp = key - '0' + 10;
+ rc_send();
+ return true;
+ } else if (key >= '0' && key <= '6') {
+ rc_temp = key - '0' + 20;
+ rc_send();
+ return true;
+ } else if (key == '&') {
+ rc_temp = 27;
+ rc_send();
+ return true;
+ } else if (key == '*') {
+ rc_temp = 28;
+ rc_send();
+ return true;
+ } else if (key == '(') {
+ rc_temp = 29;
+ rc_send();
+ return true;
+ } else if (key == ')') {
+ rc_temp = 30;
+ rc_send();
+ return true;
+ }
+ return false;
+}
+