Add rev 01 errata to README

README.MD

@@ -1 +1,14 @@
 # WS2812B light signal - CPU Board
+
+Board to run [colorchord2](https://github.com/cnlohr/colorchord) on a string of WS2812B LEDs with live line-in audio.
+
+## Errata (Rev 01)
+
+* Opamp inverting / non-inverting inputs are swapped
+	* Workaround: Lift pads 2 and 3, and 5 and 6, and connect them crossed using magnet wire.
+* Opamp is not rail-to-rail and does not allow to use the ADC in full range
+	* Workaround: Only use limited range -640 to 520.
+* LED footprint is wrong.
+	* Workaround: Flip 180 degrees and solder shifted onto the right pads, then use magnet wire to connect the remaining two pads.
+* Serial boot loader non-functional (uses incompatible UART I/Os).
+	* Workaround: Program via JTAG / SWD.

firmware/lib/systems.c

@@ -262,3 +262,29 @@ void ConfigureGPIO( uint8_t gpio, int parameters )
 	GPIO_Init(GPIOOf(gpio), &GPIO_InitStructure);
 }
 
+void JumpToBootloader(void) {
+	// Many thanks to https://stm32f4-discovery.net/2017/04/tutorial-jump-system-memory-software-stm32/
+
+	void (*SysMemBootJump)(void);
+	volatile uint32_t addr = 0x1FFF0000;
+
+	RCC_DeInit();
+
+	// Disable and reset systick
+	SysTick->CTRL = 0;
+	SysTick->LOAD = 0;
+	SysTick->VAL = 0;
+
+	__disable_irq();
+
+	// Remap system memory	
+	SYSCFG->MEMRMP = 0x01;
+
+	SysMemBootJump = (void (*)(void)) (*((uint32_t *)(addr + 4)));
+
+	// Set main stack pointer
+	__set_MSP(*(uint32_t *)addr);
+
+	// Jump
+	SysMemBootJump();
+}

firmware/lib/systems.h

@@ -54,8 +54,10 @@ void ConfigureGPIO( gpio gpio, int parameters );
 #endif
 
 void ConfigureUART();
-
 void ConfigureLED();
+
+void JumpToBootloader(void);
+
 #define LED_TOGGLE {GPIOOf(LEDPIN)->ODR^=(1<<((LEDPIN)&0x0f));}
 #define LED_ON     GPIOOn(LEDPIN)
 #define LED_OFF    GPIOOff(LEDPIN)