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authorjaseg <git@jaseg.net>2019-04-23 22:46:38 +0900
committerjaseg <git@jaseg.net>2019-04-23 22:46:38 +0900
commitcb4a682e557b6e983cade29817ac9cb9e14cf49b (patch)
treeaa4fec461f321f7dc574e0549da0734a87c3b8e6 /driver_fw
parentc6bf873e9f938c3dcab0347f8cf6cc76dcff2264 (diff)
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driver: Add ac bc framing and a bunch of comments
Diffstat (limited to 'driver_fw')
-rw-r--r--driver_fw/main.c100
1 files changed, 66 insertions, 34 deletions
diff --git a/driver_fw/main.c b/driver_fw/main.c
index d64bca4..ef01bfb 100644
--- a/driver_fw/main.c
+++ b/driver_fw/main.c
@@ -75,8 +75,6 @@ enum STATUS_LEDS {
static void set_status_leds(uint8_t val) {
/* Reset strobe. Will be set in systick handler */
GPIOA->BRR = 1<<4;
- //for (int i=0; i<100; i++)
- // asm volatile ("nop");
/* Workaround for *nasty* hardware behavior: If SPI data width is configured as 8 bit but DR is written as 16
* bit, SPI actually sends 16 clock cycles. Thus, we have to make sure the compiler emits a 8-bit write here.
* Thanks, TI! */
@@ -102,7 +100,12 @@ int main(void) {
NVIC_EnableIRQ(SysTick_IRQn);
NVIC_SetPriority(SysTick_IRQn, 3<<5);
- /* GPIO setup */
+ /* GPIO setup
+ *
+ * Note: since we have quite a bunch of pin constraints we can't actually use complementary outputs for the
+ * complementary MOSFET driver control signals (CTRL_A & CTRL_B). Instead, we use two totally separate output
+ * channels (1 & 4) and emulate the dead-time generator in software.
+ */
GPIOA->MODER |=
(3<<GPIO_MODER_MODER0_Pos) /* PA0 - Vboot to ADC */
| (2<<GPIO_MODER_MODER1_Pos) /* PA1 - RS485 DE */
@@ -135,9 +138,6 @@ int main(void) {
(3<<GPIO_OSPEEDR_OSPEEDR1_Pos)
| (3<<GPIO_OSPEEDR_OSPEEDR2_Pos);
- /* Note: since we have quite a bunch of pin constraints we can't actually use complementary outputs for the
- * complementary MOSFET driver control signals (CTRL_A & CTRL_B). Instead, we use two totally separate output
- * channels (1 & 4) and emulate the dead-time generator in software. */
GPIOB->MODER |=
(2<<GPIO_MODER_MODER1_Pos); /* PB1 - CTRL_B to TIM 3 ch 4 */
@@ -165,50 +165,56 @@ int main(void) {
using a Java(TM) GUI. */
i2c_enable(I2C1);
lcd1602_init();
- ina226_init();
- mcp9801_init();
- /* The MCP9801 temperature sensor is initialized below in the SysTick ISR since it needs a few milliseconds to
- * powerup. */
+ ina226_init(); /* Current/voltage monitor */
+ mcp9801_init(); /* MOSFET temperature. Placed between middle two low-side MOSFETs. */
/* TIM3 is used to generate the MOSFET driver control signals */
/* TIM3 running off 48MHz APB1 clk, T=20.833ns */
TIM3->CR1 = 0; /* Disable ARR preload (double-buffering) */
TIM3->PSC = 48-1; /* Prescaler 48 -> f=1MHz/T=1us */
TIM3->DIER = TIM_DIER_UIE; /* Enable update (overflow) interrupt */
+
+ /* Set both CCRs to 0xffff to ensure both bridge halves are turned off after we enable the timer. If we don't do
+ * this, we will cause a very low-ohm short circuit that at best will trigger our power supply's short-circuit or
+ * over-current protection right after power-on but at worst will detonate the mosfets. */
TIM3->CCR1 = 0xffff;
TIM3->CCR4 = 0xffff;
- TIM3->CCMR1 = 6<<TIM_CCMR1_OC1M_Pos | TIM_CCMR1_OC1PE; /* Configure output compare unit 1 to PWM mode 1, enable CCR1 preload */
- TIM3->CCMR2 = 6<<TIM_CCMR2_OC4M_Pos | TIM_CCMR2_OC4PE; /* Configure output compare unit 4 to PWM mode 1, enable CCR4 preload */
- TIM3->CCER = TIM_CCER_CC1E | TIM_CCER_CC1P | TIM_CCER_CC4E | TIM_CCER_CC4P; /* Confiugre CH1 to complementary outputs */
- TIM3->BDTR = TIM_BDTR_MOE; /* Enable MOE on next update event, i.e. on initial timer load. */
+ /* Configure output compare unit 1 to PWM mode 1, enable CCR1 preload */
+ TIM3->CCMR1 = 6<<TIM_CCMR1_OC1M_Pos | TIM_CCMR1_OC1PE;
+ /* Configure output compare unit 4 to PWM mode 1, enable CCR4 preload */
+ TIM3->CCMR2 = 6<<TIM_CCMR2_OC4M_Pos | TIM_CCMR2_OC4PE;
+ /* Confiugre CH1 to complementary outputs */
+ TIM3->CCER = TIM_CCER_CC1E | TIM_CCER_CC1P | TIM_CCER_CC4E | TIM_CCER_CC4P;
+ /* Enable MOE on next update event, i.e. on initial timer load. */
+ TIM3->BDTR = TIM_BDTR_MOE;
+ /* Enable timer */
TIM3->CR1 |= TIM_CR1_CEN;
- TIM3->ARR = 800-1; /* Set f=2.5kHz/T=0.4ms */
+ /* Set f=2.5kHz/T=0.4ms */
+ TIM3->ARR = 800-1;
+ /* Initialize AC protocol state machine in TIM3 ISR with the AC protocol comma */
xfr_8b10b_encode_reset(&txstate.st);
txstate.current_symbol = xfr_8b10b_encode(&txstate.st, K28_1) | 1<<10;
+ /* The timer is still stopped. Start it by manually triggering an update event. */
TIM3->EGR |= TIM_EGR_UG;
- lcd_write_str(0, 0, "8seg driver");
- lcd_write_str(0, 1, "initialized \xbc");
-
NVIC_EnableIRQ(TIM3_IRQn);
NVIC_SetPriority(TIM3_IRQn, 2<<4);
+ lcd_write_str(0, 0, "8seg driver");
+ lcd_write_str(0, 1, "initialized \xbc");
while (42) {
- if (sys_flag_1Hz) {
+ if (sys_flag_1Hz) { /* Update display every second */
sys_flag_1Hz = 0;
char buf[17];
-
int temp = mcp9801_read_mdegC();
int deg = temp/1000;
int frac = (temp%1000)/100;
mini_snprintf(buf, sizeof(buf), "Temp: %d.%01d\xdf""C" LCD_FILL, deg, frac);
lcd_write_str(0, 0, buf);
-
mini_snprintf(buf, sizeof(buf), "I=%dmA U=%dmV" LCD_FILL, ina226_read_i()*INA226_I_LSB_uA/1000, ina226_read_v()*INA226_VB_LSB_uV/1000);
lcd_write_str(0, 1, buf);
-
}
}
}
@@ -228,33 +234,58 @@ static int flipbits10(int in) {
}
+#define BACKCHANNEL_INTERVAL 10
+
void TIM3_IRQHandler() {
static int txpos = -1;
static unsigned int tx_start_tick = 0;
- static uint8_t txbuf[3] = {0x01, 0x05, 0x01};
+ static uint8_t txbuf[2] = {0x04, 0x05};
+ static int backchannel_counter = 0;
TIM3->SR &= ~TIM_SR_UIF;
int sym = txstate.current_symbol;
int bit = sym&1;
sym >>= 1;
if (sym == 1) { /* last bit shifted out */
- if (txpos == -1)
- sym = xfr_8b10b_encode(&txstate.st, -K28_1);
- else
- sym = xfr_8b10b_encode(&txstate.st, txbuf[txpos]);
-
- txpos++;
- if (txpos >= sizeof(txbuf)/sizeof(txbuf[0])) {
- frame_duration_us = (sys_time_tick - tx_start_tick) * 10 * 1000;
- tx_start_tick = sys_time_tick;
- txpos = -1;
+
+ /* Insert the backchannel sync control symbol K.28.2 once every BACKCHANNEL_INTERVAL symbols independent from AC
+ * forward channel protocol framing. The backchannel sync control symbol is different from the AC protocol comma
+ * K.28.1. The backchannel sync control symbol is not a comma, so the 8b10b receiver cannot lock on it. The only
+ * practical implication of this is that after powerup or other loss of sync, the receiver will only lock on the
+ * backchannel sync once the first AC forward-channel protocol frame has been begun. Since all backchannel comm
+ * is triggered by the driver anyway this should not be noticeable in practice.
+ */
+ backchannel_counter++;
+ if (backchannel_counter == BACKCHANNEL_INTERVAL) {
+ backchannel_counter = 0;
+ sym = xfr_8b10b_encode(&txstate.st, -K28_2); /* TODO factor out backchannel comma into constant */
+
+ } else {
+
+ if (txpos == -1)
+ sym = xfr_8b10b_encode(&txstate.st, -K28_1); /* TODO factor out comma into constant */
+ else
+ sym = xfr_8b10b_encode(&txstate.st, txbuf[txpos]);
+
+ txpos++;
+ if (txpos >= sizeof(txbuf)/sizeof(txbuf[0])) {
+ frame_duration_us = (sys_time_tick - tx_start_tick) * 10 * 1000;
+ tx_start_tick = sys_time_tick;
+ txpos = -1;
+ }
}
+ /* Append one '1' bit as an end-of-symbol marker for this state machine. This bit is not actually transmitted. */
sym = flipbits10(sym) | 1<<10;
}
txstate.current_symbol = sym;
+ /* FIXME factor out into header, or even make configurable */
#define DEAD_TIME 100
+ /* Set both CCRs to values for opposing polarities. The dead time is always inserted at the beginning of the timer
+ * cycle due to the way the capture/compare unit PWM machinery works. By setting the CCR to 0xffff we make sure the
+ * output is never turned on, since 0xffff is larger than the ARR/counter top value.
+ */
TIM3->CCR1 = bit ? 0xffff : DEAD_TIME;
TIM3->CCR4 = bit ? DEAD_TIME : 0xffff;
}
@@ -285,7 +316,7 @@ void SysTick_Handler(void) {
/* This is a hack. We could use the SPI interrupt here if that didn't fire at the start instead of end of transmission.... -.- */
if (sys_time_tick&1) {
- uint8_t val = (sys_time_ms >= 500) ? STATUS_LED_OPERATION : 0;
+ uint8_t val = (sys_time_ms >= 300) ? STATUS_LED_OPERATION : 0;
if (comm_led_ctr) {
comm_led_ctr--;
@@ -299,6 +330,7 @@ void SysTick_Handler(void) {
set_status_leds(val);
} else {
+ /* Reset strobe for the status LED shift register. Reset in set_status_leds. */
GPIOA->BSRR = 1<<4;
}
}