board bringup: adc, usart working

1 files changed, 125 insertions, 0 deletions

diff --git a/gm_platform/fw/adc.c b/gm_platform/fw/adc.c
new file mode 100644
index 0000000..547089b
--- /dev/null
+++ b/gm_platform/fw/adc.c
@@ -0,0 +1,125 @@
+/* Megumin LED display firmware
+ * Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "adc.h"
+
+#include <stdbool.h>
+#include <stdlib.h>
+
+volatile uint16_t adc_buf[ADC_BUFSIZE];
+
+static void adc_dma_init(int burstlen);
+static void adc_timer_init(int psc, int ivl);
+
+
+/* Mode that can be used for debugging */
+void adc_configure_scope_mode(int sampling_interval_ns) {
+	adc_dma_init(sizeof(adc_buf)/sizeof(adc_buf[0]));
+
+    /* Clock from PCLK/4 instead of the internal exclusive high-speed RC oscillator. */
+    ADC1->CFGR2 = (2<<ADC_CFGR2_CKMODE_Pos); /* Use PCLK/4=12MHz */
+    /* Sampling time 239.5 ADC clock cycles -> total conversion time 38.5us*/
+    ADC1->SMPR  = (7<<ADC_SMPR_SMP_Pos);
+
+	/* Setup DMA and triggering */
+	/* Trigger from TIM1 TRGO */
+    ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | (2<<ADC_CFGR1_EXTEN_Pos) | (1<<ADC_CFGR1_EXTSEL_Pos);
+    ADC1->CHSELR = ADC_CHSELR_CHSEL2;
+	/* Perform self-calibration */
+    ADC1->CR |= ADC_CR_ADCAL;
+    while (ADC1->CR & ADC_CR_ADCAL)
+        ;
+	/* Enable conversion */
+    ADC1->CR |= ADC_CR_ADEN;
+    ADC1->CR |= ADC_CR_ADSTART;
+
+	/* An ADC conversion takes 1.1667us, so to be sure we don't get data overruns we limit sampling to every 1.5us.
+	Since we don't have a spare PLL to generate the ADC sample clock and re-configuring the system clock just for this
+	would be overkill we round to 250ns increments. The minimum sampling rate is about 60Hz due to timer resolution. */
+	int cycles = sampling_interval_ns > 1500 ? sampling_interval_ns/250 : 6;
+	if (cycles > 0xffff)
+		cycles = 0xffff;
+	adc_timer_init(12/*250ns/tick*/, cycles);
+}
+
+/* FIXME figure out the proper place to configure this. */
+#define ADC_TIMER_INTERVAL_US 20
+
+static void adc_dma_init(int burstlen) {
+    /* Configure DMA 1 Channel 1 to get rid of all the data */
+    DMA1_Channel1->CPAR = (unsigned int)&ADC1->DR;
+    DMA1_Channel1->CMAR = (unsigned int)&adc_buf;
+    DMA1_Channel1->CNDTR = burstlen;
+    DMA1_Channel1->CCR = (0<<DMA_CCR_PL_Pos);
+    DMA1_Channel1->CCR |=
+          DMA_CCR_CIRC /* circular mode so we can leave it running indefinitely */
+        | (1<<DMA_CCR_MSIZE_Pos) /* 16 bit */
+        | (1<<DMA_CCR_PSIZE_Pos) /* 16 bit */
+        | DMA_CCR_MINC
+        | DMA_CCR_TCIE; /* Enable transfer complete interrupt. */
+
+    /* triggered on transfer completion. We use this to process the ADC data */
+    NVIC_EnableIRQ(DMA1_Channel1_IRQn);
+    NVIC_SetPriority(DMA1_Channel1_IRQn, 2<<5);
+
+    DMA1_Channel1->CCR |= DMA_CCR_EN; /* Enable channel */
+}
+
+static void adc_timer_init(int psc, int ivl) {
+    TIM1->BDTR  = TIM_BDTR_MOE; /* MOE is needed even though we only "output" a chip-internal signal TODO: Verify this. */
+    TIM1->CCMR2 = (6<<TIM_CCMR2_OC4M_Pos); /* PWM Mode 1 to get a clean trigger signal */
+    TIM1->CCER  = TIM_CCER_CC4E; /* Enable capture/compare unit 4 connected to ADC */
+    TIM1->CCR4  = 1; /* Trigger at start of timer cycle */
+	/* Set prescaler and interval */
+    TIM1->PSC   = psc-1;
+    TIM1->ARR   = ivl-1;
+    /* Preload all values */
+    TIM1->EGR  |= TIM_EGR_UG;
+    TIM1->CR1   = TIM_CR1_ARPE;
+    /* And... go! */
+    TIM1->CR1  |= TIM_CR1_CEN;
+}
+
+/* This acts as a no-op that provides a convenient point to set a breakpoint for the debug scope logic */
+static void gdb_dump(void) {
+}
+
+void DMA1_Channel1_IRQHandler(void) {
+    /* Clear the interrupt flag */
+    DMA1->IFCR |= DMA_IFCR_CGIF1;
+    gdb_dump();
+    
+    /*
+    static int debug_buf_pos = 0;
+    if (st->sync) {
+        if (debug_buf_pos < NCH) {
+                debug_buf_pos = NCH;
+        } else {
+            adc_buf[debug_buf_pos++] = symbol;
+
+            if (debug_buf_pos >= sizeof(adc_buf)/sizeof(adc_buf[0])) {
+                debug_buf_pos = 0;
+                st->sync = 0;
+                gdb_dump();
+                for (int i=0; i<sizeof(adc_buf)/sizeof(adc_buf[0]); i++)
+                    adc_buf[i] = -255;
+            }
+        }
+    }
+    */
+}
+