gm_platform: Add support for OCXO and GPS sync

4 files changed, 98 insertions, 28 deletions

diff --git a/gm_platform/fw/Makefile b/gm_platform/fw/Makefile
index ea874eb..77b2a09 100644
--- a/gm_platform/fw/Makefile
+++ b/gm_platform/fw/Makefile
@@ -40,7 +40,7 @@ LIBS = -lgcc
 # Technically we're using an STM32F030F4, but apart from the TSSOP20 package that one is largely identical to the
 # STM32F030*6 and there is no separate device header provided for it, so we're faking a *6 device here. This is
 # even documented in stm32f0xx.h. Thanks ST!
-CFLAGS += -DSTM32F030x6 -DHSE_VALUE=8000000
+CFLAGS += -DSTM32F030x6 -DHSE_VALUE=19440000
 
 LDFLAGS += -Tstm32_flash.ld
 CFLAGS += -I$(CMSIS_DEV_PATH)/Include -I$(CMSIS_PATH)/Include -I$(HAL_PATH)/Inc -Iconfig -Wno-unused -I../common
diff --git a/gm_platform/fw/adc.c b/gm_platform/fw/adc.c
index e3aba5b..ab9d6b5 100644
--- a/gm_platform/fw/adc.c
+++ b/gm_platform/fw/adc.c
@@ -25,6 +25,7 @@
 static struct __attribute__((__packed__)) hl_adc_pkt {
     struct ll_pkt ll;
     uint16_t seq;
+    int32_t gps_1pps_period_sysclk;
     volatile uint16_t data[32];
 } adc_pkt[2];
 static uint16_t current_seq = 0;
@@ -99,7 +100,7 @@ static void adc_timer_init(int psc, int ivl) {
     TIM1->PSC   = psc-1;
     TIM1->ARR   = ivl-1;
     /* Preload all values */
-    TIM1->EGR  |= TIM_EGR_UG;
+    TIM1->EGR   = TIM_EGR_UG;
     TIM1->CR1   = TIM_CR1_ARPE;
     /* And... go! */
     TIM1->CR1  |= TIM_CR1_CEN;
@@ -118,6 +119,7 @@ void DMA1_Channel1_IRQHandler(void) {
     gdb_dump();
 
     adc_pkt[!current_buf].seq = current_seq++;
+    adc_pkt[!current_buf].gps_1pps_period_sysclk = gps_1pps_period_sysclk;
     /* Ignore return value since we can't do anything here. Overruns are logged in serial.c. */
     usart_send_packet_nonblocking(&adc_pkt[!current_buf].ll, sizeof(adc_pkt[!current_buf]));
     
diff --git a/gm_platform/fw/global.h b/gm_platform/fw/global.h
index 9c454bc..28ac6cd 100644
--- a/gm_platform/fw/global.h
+++ b/gm_platform/fw/global.h
@@ -57,5 +57,6 @@ union leds {
 };
 
 extern volatile union leds leds;
+extern volatile int32_t gps_1pps_period_sysclk;
 
 #endif/*__GLOBAL_H__*/
diff --git a/gm_platform/fw/main.c b/gm_platform/fw/main.c
index 74f305b..811b27f 100644
--- a/gm_platform/fw/main.c
+++ b/gm_platform/fw/main.c
@@ -22,25 +22,11 @@
 
 volatile unsigned int sys_time_seconds = 0;
 volatile union leds leds;
+volatile int32_t gps_1pps_period_sysclk = -1;
 
 int main(void) {
-    RCC->CR |= RCC_CR_HSEON;
-    while (!(RCC->CR&RCC_CR_HSERDY));
-    RCC->CFGR &= ~RCC_CFGR_PLLMUL_Msk & ~RCC_CFGR_SW_Msk & ~RCC_CFGR_PPRE_Msk & ~RCC_CFGR_HPRE_Msk;
-    RCC->CFGR |= ((6-2)<<RCC_CFGR_PLLMUL_Pos) | RCC_CFGR_PLLSRC_HSE_PREDIV; /* PLL x6 -> 48.0MHz */
-    RCC->CR |= RCC_CR_PLLON;
-    while (!(RCC->CR&RCC_CR_PLLRDY));
-    RCC->CFGR |= (2<<RCC_CFGR_SW_Pos);
-    SystemCoreClockUpdate();
-    SysTick_Config(SystemCoreClock/10); /* 100ms interval */
-    NVIC_EnableIRQ(SysTick_IRQn);
-    NVIC_SetPriority(SysTick_IRQn, 3<<5);
-
-    /* Turn on lots of neat things */
-    RCC->AHBENR  |= RCC_AHBENR_DMAEN | RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN | RCC_AHBENR_FLITFEN | RCC_AHBENR_CRCEN;
-    RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN | RCC_APB2ENR_ADCEN | RCC_APB2ENR_SPI1EN | RCC_APB2ENR_DBGMCUEN |\
-                    RCC_APB2ENR_TIM1EN | RCC_APB2ENR_TIM16EN | RCC_APB2ENR_USART1EN;
-    RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
+    RCC->AHBENR  |= RCC_AHBENR_GPIOAEN;
+    RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;
 
     GPIOA->MODER |=
           (3<<GPIO_MODER_MODER2_Pos)  /* PA2  - LINE_MEAS */
@@ -63,9 +49,6 @@ int main(void) {
     GPIOA->AFR[0] = (0<<GPIO_AFRL_AFRL5_Pos) | (0<<GPIO_AFRL_AFRL6_Pos) | (0<<GPIO_AFRL_AFRL7_Pos);
     GPIOA->AFR[1] = (1<<8) | (1<<4);
 
-    GPIOB->MODER |=
-          (0<<GPIO_MODER_MODER1_Pos); /* PB0  - LINE_POL */
-
     SPI1->CR1 =
           SPI_CR1_SSM
         | SPI_CR1_SSI
@@ -75,8 +58,38 @@ int main(void) {
         | SPI_CR1_MSTR;
     SPI1->CR2 = (7<<SPI_CR2_DS_Pos);
     SPI1->CR1 |= SPI_CR1_SPE;
+    *((volatile uint8_t*)&(SPI1->DR)) = 0xff;
+
+    for (int i=0; i<1000000; i++)
+        ;
+
+    RCC->CR |= RCC_CR_HSEBYP;
+    RCC->CR |= RCC_CR_HSEON;
+    RCC->CFGR &= ~RCC_CFGR_PLLMUL_Msk & ~RCC_CFGR_SW_Msk & ~RCC_CFGR_PPRE_Msk & ~RCC_CFGR_HPRE_Msk;
+    /* PLL config: 19.44MHz /2 x5 -> 48.6MHz */
+    RCC->CFGR |= ((5-2)<<RCC_CFGR_PLLMUL_Pos) | RCC_CFGR_PLLSRC_HSE_PREDIV;
+    RCC->CFGR2 = ((2-1)<<RCC_CFGR2_PREDIV_Pos);
+    RCC->CR |= RCC_CR_PLLON;
+    while (!(RCC->CR&RCC_CR_PLLRDY));
+    RCC->CFGR |= (2<<RCC_CFGR_SW_Pos);
+    SystemCoreClockUpdate();
+    SysTick_Config(SystemCoreClock/10); /* 100ms interval */
+    NVIC_EnableIRQ(SysTick_IRQn);
+    NVIC_SetPriority(SysTick_IRQn, 3<<5);
+
+    /* Turn on lots of neat things */
+    RCC->AHBENR  |= RCC_AHBENR_DMAEN | RCC_AHBENR_GPIOBEN | RCC_AHBENR_FLITFEN | RCC_AHBENR_CRCEN;
+    RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN | RCC_APB2ENR_ADCEN  | RCC_APB2ENR_DBGMCUEN |\
+                    RCC_APB2ENR_TIM1EN | RCC_APB2ENR_TIM16EN | RCC_APB2ENR_USART1EN;
+    RCC->APB1ENR |= RCC_APB1ENR_TIM3EN | RCC_APB1ENR_TIM14EN;
+
+    GPIOB->MODER |=
+          (2<<GPIO_MODER_MODER1_Pos); /* PB0  - GPS 1pps input */
+    GPIOB->AFR[0] = (0<<GPIO_AFRL_AFRL1_Pos);
+    GPIOB->PUPDR = 2<<GPIO_PUPDR_PUPDR1_Pos;
 
     TIM16->CR2 = 0;
+
     TIM16->DIER = TIM_DIER_UIE | TIM_DIER_CC1IE;
     TIM16->CCMR1 = 0;
     TIM16->CCR1 = 32;
@@ -85,17 +98,70 @@ int main(void) {
     TIM16->CR1 = TIM_CR1_CEN;
 
     NVIC_EnableIRQ(TIM16_IRQn);
-    NVIC_SetPriority(TIM16_IRQn, 3<<5);
+
+    TIM14->CCMR1 = (1<<TIM_CCMR1_CC1S_Pos) | (3<<TIM_CCMR1_IC1F_Pos);
+    TIM14->CCER = TIM_CCER_CC1E;
+    TIM14->PSC = 1;
+    TIM14->ARR = 0xffff;
+    TIM14->DIER = TIM_DIER_CC1IE | TIM_DIER_UIE;
+    TIM14->EGR = TIM_EGR_UG;
+    TIM14->CR1  |= TIM_CR1_CEN;
+
+    NVIC_EnableIRQ(TIM14_IRQn);
 
     adc_configure_scope_mode(1000000);
 
     usart_dma_init();
 
     while (42) {
-        //int pol = GPIOB->IDR & (1<<1); /* Sample current polarity */
-        //leds.error = pol ? 100 : 0;
-        //for (int i=0; i<10000; i++) ;
-        //leds.error = 100;
+        /* Do nothing and let the interrupts do all the work. */
+    }
+}
+
+void tim14_sr_cc1of(void) {} /* gdb hook */
+
+void TIM14_IRQHandler(void) {
+    static uint32_t gps_1pps_period = 0;
+    static uint32_t update_inc = 0;
+    static bool in_sync = false;
+
+    uint32_t sr = TIM14->SR;
+    if (sr & TIM_SR_CC1OF) {
+        TIM14->SR &= ~(TIM_SR_CC1IF | TIM_SR_CC1OF);
+        tim14_sr_cc1of();
+    } else if (sr & TIM_SR_CC1IF) { /* CC1 event (GPS 1pps input) */
+        /* Don't reset update event: If update event arrives while CC1 event is being processed leave UIF set to process
+         * update event immediately after return from ISR. */
+        uint16_t ccr = TIM14->CCR1;
+        if (in_sync) {
+            uint32_t new_period = gps_1pps_period + ccr;
+            if (new_period < 20000000 || new_period > 30000000) { /* Signal out of range */
+                in_sync = false;
+                gps_1pps_period_sysclk = -1;
+                gps_1pps_period = (uint32_t)-1;
+            } else {
+                gps_1pps_period_sysclk = new_period;
+                gps_1pps_period = 0;
+                update_inc = 0x10000 - ccr; /* remaining cycles in this period */
+                leds.pps = 200; /* ms */
+            }
+        } else {
+            gps_1pps_period = 0;
+            update_inc = 0x10000 - ccr; /* remaining cycles in this period */
+            in_sync = true;
+        }
+
+    } else { /* update */
+        TIM14->SR &= ~TIM_SR_UIF;
+        if (in_sync) {
+            gps_1pps_period += update_inc;
+            if (gps_1pps_period > 30000000) { /* Signal out of range */
+                in_sync = false;
+                gps_1pps_period_sysclk = -1;
+                gps_1pps_period = (uint32_t)-1;
+            }
+        }
+        update_inc = 0x10000;
     }
 }
 
@@ -151,7 +217,8 @@ void SysTick_Handler(void) {
     if (n++ == 10) {
         n = 0;
         sys_time_seconds++;
-        leds.pps = 200; /* ms */
+        if (gps_1pps_period_sysclk < 0)
+            leds.pps = 200; /* ms */
     }
 }