updated documentation

Author: lujji

Makefile

@@ -1,7 +1,6 @@
 MCU ?= stm8s003f3
 ARCH = stm8
 
-F_CPU   ?= 16000000
 TARGET  ?= main.ihx
 
 SRCS    := $(wildcard *.c)
@@ -15,8 +14,7 @@ LD       = sdld
 AS       = sdasstm8
 OBJCOPY  = sdobjcopy
 ASFLAGS  = -plosgff
-CFLAGS   = -m$(ARCH) -p$(MCU)
-CFLAGS  += -DF_CPU=$(F_CPU)UL -I.
+CFLAGS   = -m$(ARCH) -p$(MCU) -I.
 CFLAGS  += --stack-auto --noinduction --use-non-free --noinvariant --opt-code-size
 LDFLAGS  = -m$(ARCH) -l$(ARCH) --out-fmt-ihx
 LDFLAGS += -Wl-bIVT=0x8000 -Wl-bGSINIT=0x8080
@@ -45,7 +43,7 @@ size:
 
 # enable write-protection on first 10 pages
 opt-set:
-	@echo '0x00 0x0a 0xf5 0x00 0xff 0x00 0xff 0x00 0xff 0x00 0xff' | xxd -r > opt.bin
+	@echo '0x00 0x09 0xf6 0x00 0xff 0x00 0xff 0x00 0xff 0x00 0xff' | xxd -r > opt.bin
 	stm8flash -c stlinkv2 -p stm8s003f3 -s opt -w opt.bin
 
 # reset option-bytes to factory defaults

README.md

@@ -1,9 +1,9 @@
 # stm8-bootloader
-Serial bootloader for STM8S microcontrollers.
+Serial bootloader for STM8S microcontrollers. A detailed write-up on this bootloader is posted [here](https://lujji.github.io/blog/serial-bootloader-for-stm8).
 
 ## Features
 
-* **small** - fits in 9 pages (547 bytes w/ SDCC v3.6.8 #9951)
+* **small** - fits in 547 bytes (SDCC v3.6.8 #9951)
 * **fast** - uploads 4k binary in 1 second @115200bps
 * **configurable** - can be adjusted for parts with different flash block size
 
@@ -29,7 +29,7 @@ Build and flash the bootloader:
 $ make && make flash
 ```
 
-Enable write-protection (UBC) on pages 0-10:
+Enable write-protection (UBC) on pages 0-9:
 
 ``` bash
 $ make opt-set

config.h

@@ -5,6 +5,10 @@
 
 #define BAUDRATE        115200
 
+/* internal RC oscillator, CKDIVR = 0 */
+#define F_CPU           16000000UL
+#define UART_DIV         ((F_CPU + BAUDRATE / 2) / BAUDRATE)
+
 /* application address */
 #define BOOT_ADDR       0x8280
 

main.c

@@ -3,8 +3,6 @@
 #include "stm8s.h"
 #include "ram.h"
 
-#define UART_DIV ((F_CPU + BAUDRATE / 2) / BAUDRATE)
-
 static uint8_t CRC;
 static uint8_t ivt[128];
 static uint8_t f_ram[128];