WIP code

FLASH OPTR write routine implemented and tested.
Fixed wrong GPIO output values initialization.

include/testo.h

@@ -48,7 +48,7 @@
 #define CONF_MODE_AN		ADC_CHSELR_CHSEL7
 
 #define RGBSEL0_PORT		GPIOA
-#define RGBSEL0_PIN			12			// output, default low
+#define RGBSEL0_PIN			12			// output, default high
 
 #define UART_PORT			GPIOA
 #define UART_DEV			USART1
@@ -64,7 +64,7 @@
 #define CONF_SET0_AN		ADC_CHSELR_CHSEL8
 
 #define RGBSEL1_PORT		GPIOB
-#define RGBSEL1_PIN			1			// output, default low
+#define RGBSEL1_PIN			1			// output, default high
 
 
 #define PROBESEL_PORT		GPIOF

lib/py32f0xx-ll/src/py32f0xx_ll_flash.c

@@ -871,7 +871,7 @@ ErrorStatus LL_FLASH_OBProgram(FLASH_OBProgramInitTypeDef *pOBInit)
   FLASH->CR|=FLASH_CR_OPTSTRT;
 
   /* set bit EOPIE */
-  // FLASH->CR|=FLASH_CR_EOPIE;
+  FLASH->CR|=FLASH_CR_EOPIE;
 
   /* trigger program */
   *((__IO uint32_t *)(0x40022080))=0xff;

py32f030x6.ld

@@ -110,7 +110,8 @@ SECTIONS
     _sdata = .;        /* create a global symbol at data start */
     *(.data)           /* .data sections */
     *(.data*)          /* .data* sections */
-
+    *(.ramfunc*)
+    
     . = ALIGN(4);
     _edata = .;        /* define a global symbol at data end */
   } >RAM AT> FLASH

py32f030x6_bl.ld

@@ -108,6 +108,7 @@ SECTIONS
     _sdata = .;        /* create a global symbol at data start */
     *(.data)           /* .data sections */
     *(.data*)          /* .data* sections */
+    *(.ramfunc*)
 
     . = ALIGN(4);
     _edata = .;        /* define a global symbol at data end */

src/flash.c

@@ -47,20 +47,12 @@ void flash_optr_checkfix()
     }
 }
 
-/*
- * manually load values into flash option byte, to configure
- * the BOR and configure the reset pin to be PF2.
- */
-void flash_optr_set()
-{
-    FLASH->OPTR &= (FLASH_OPTR_BOR_EN_Msk | FLASH_OPTR_BOR_LEV_Msk | FLASH_OPTR_NRST_MODE_Msk);
-    FLASH->OPTR |=  OB_BOR_ENABLE | OB_BOR_LEVEL_2p3_2p4 | OB_RESET_MODE_GPIO;
-}
-
-void flash_init()
+void flash_write_timings_8MHz()
 {
     // load flash write timings for 8MHz operation
     // (these are listed in the datasheet)
+    // note: if you decide to operate at a different frequency, then either
+    //       update these values, or reduce speed to 8MHz when writing to flash
     FLASH->TS0  = 0x3c;
     FLASH->TS2P = 0x3c;
     FLASH->TS3  = 0x3c;
@@ -72,4 +64,45 @@ void flash_init()
     FLASH->SMERTPE = 0x5dc0;
     FLASH->PRGTPE  = 0x1f40;
     FLASH->PRETPE  = 0x640;
+}
+
+__attribute__ ((long_call, section(".ramfunc"))) void flash_init()
+{
+    // configure flash timings
+    flash_write_timings_8MHz();
+
+    // is the PF2/NRST pin configured as reset?
+    if ((FLASH->OPTR & FLASH_OPTR_NRST_MODE) == OB_RESET_MODE_RESET) {
+        // it is but shouldn't be, so let's configure it as GPIO.
+        
+        // per datasheet, we must unlock FLASH->CR and then unlock OPTLOCK
+        FLASH->KEYR = FLASH_KEY1;
+        FLASH->KEYR = FLASH_KEY2;
+        if (FLASH->CR & FLASH_CR_LOCK) return;      // somehow, flash is still locked
+
+        FLASH->OPTKEYR = FLASH_OPTKEY1;
+        FLASH->OPTKEYR = FLASH_OPTKEY2;
+        if (FLASH->CR & FLASH_CR_OPTLOCK) return;	// somehow, OB is still locked
+    
+        // write new OPTR values
+        FLASH->OPTR = OB_RESET_MODE_GPIO | OB_WWDG_SW | OB_IWDG_SW | OB_BOR_LEVEL_2p3_2p4 | FLASH_OPTR_RDP_LEVEL_0;
+                        // OB_BOR_ENABLE
+
+        // enable EOPIE (per DS, EOP isn't set unless EOPIE is set)
+        // and signal that we want to write option bits,
+        // then trigger the write by writing to a random address shown in the DS
+        FLASH->CR |= FLASH_CR_EOPIE | FLASH_CR_OPTSTRT;
+        *((__IO uint32_t *)(0x40022080)) = 0x55aa55aa;
+
+        // wait for BSY to go low, then EOP to go high
+        while (FLASH->SR & FLASH_SR_BSY);
+        while (!(FLASH->SR & FLASH_SR_EOP));
+
+        // do an OBL_LAUNCH reset to load the new option bits
+        // this must be done while OPTLOCK is cleared
+        FLASH->CR |= FLASH_CR_OBL_LAUNCH;
+
+        // as the MCU should have reset, we should never get here.
+        while(1);
+    }
 }

src/main.c

@@ -27,7 +27,12 @@ static inline void gpio_init()
     // LL functions to save space.
     // though we probably don't _need_ this space...
 
-    // set I2C outputs as open drain
+    // PF2=OUT(high), low speed
+    // unused pins are analog
+    GPIOF->ODR     = (1 << 2);
+    GPIOF->MODER   = 0xFFFFFCDF;
+	
+	// set I2C outputs as open drain
     GPIOA->OTYPER  = 0x000c;
     // enable pullups on I2C outputs
     GPIOA->PUPDR   = 0x24000050;
@@ -37,6 +42,8 @@ static inline void gpio_init()
     // alternate function select
     // PA6=T3C1, PA5=T3C2, PA4=T3C3, PA3=I2C_SCL, PA2=I2C_SDA
     GPIOA->AFR[0]  = 0x01DDCC00;
+	// PA12=OUT(high)
+	GPIOA->ODR     = (1 << 12);
 
     // PA14=ALT, PA13=ALT, PA12=OUT, PA11=OUT
     // PA7=AN,   PA6=AF,   PA5=AF,   PA4=AF
@@ -45,15 +52,11 @@ static inline void gpio_init()
     GPIOA->MODER   = 0x2900EAAF;
     
 
-    // PB1=OUT, PB0=AN
+    // PB1=OUT(HIGH), PB0=AN
     // unused pins are analog, all outputs are low speed
     GPIOB->OSPEEDR = 0x00000000;
+	GPIOB->ODR     = (1 << 1);
     GPIOB->MODER   = 0xfffffff7;
-
-    // PF2=OUT(low), low speed
-    // unused pins are analog
-    GPIOF->ODR     = (1 << 2);
-    GPIOF->MODER   = 0xFFFFFCDF;
 }
 
 static inline void clk_init()
@@ -91,7 +94,7 @@ int main()
 {
     // base hardware initialization
     clk_init();
-    flash_init();   // also configures option bytes, if necessary
+    flash_init();   // also configures option bytes to enable PF2, if necessary
     gpio_init();
 
     // peripheral initialization
@@ -119,7 +122,7 @@ int main()
  * main application interrupt
  */
 
-void SysTick_Handler(void)
+__attribute__ ((long_call, section(".ramfunc"))) void SysTick_Handler(void)
 {
     uint16_t cs;