Telink TLSR8232 BLE SDK Developer Handbook
AN-19112700-E1 29 Ver.1.0.0
7) bss
“data” is followed by “bss”. Since the first array “_start_bss_” should be 16-byte aligned,
the “bss” section starts from 0x80a2a0, and its size is 0xc98, as shown in Figure 2-3.
The final variable in “bss” is “blt_ota_start_tick”, a int variable. Its address is 0x80af34,
and its size is 4-byte. Therefore the ending address of “bss” is 0x80af38, and the size of
the “bss” is 0x80af38 - 0x80a2a0 = 0xc98, as shown in Figure 2-3.
By calculation the remaining SRAM space size is 0x80c000 – 0x80af38 = 0x10c8 = 4296
bytes, from which minus 256 bytes for stack, the remaining 4040 bytes are unused.
2.1.3 MCU Address Space Access
MCU address space 0x000000 ~ 0xffffff can be accessed in the program in the following
two cases.
2.1.3.1 Peripheral Space Access
The peripheral space (register & SRAM) is directly accessed (read/write) via pointer.
u8 x = *(volatile u8*)0x800066; // read register 0x66
*(volatile u8*)0x800066 = 0x26; // write register 0x66
u32 y = *(volatile u32*)0x808000; // read SRAM 0x8000-0x8003
*(volatile u32*)0x808000 = 0x12345678; // write SRAM 0x8000-0x8003
In the program, functions including “write_reg8”, “write_reg16”, “write_reg32”,
“read_reg8”, “read_reg16” and “read_reg32”, which implement pointer operation, are
used to write or read the peripheral space correspondingly. Please see
“drivers/5316/bsp.h” for details.
Please note that for operations such as write_reg8 (0x8000), read_reg16 (0x8000) ,
whose definitions are shown as below, the base address “0x800000” is automatically
added (address line BIT(23) is 1) to ensure the access space is Register/SRAM rather
than Flash.
#define REG_BASE_ADDR 0x800000
#define write_reg8(addr,v) U8_SET((addr + REG_BASE_ADDR),v)
#define write_reg16(addr,v) U16_SET((addr + REG_BASE_ADDR),v)
#define write_reg32(addr,v) U32_SET((addr + REG_BASE_ADDR),v)
#define read_reg8(addr) U8_GET((addr + REG_BASE_ADDR))
#define read_reg16(addr) U16_GET((addr + REG_BASE_ADDR))
#define read_reg32(addr) U32_GET((addr + REG_BASE_ADDR))
Please pay attention to one thing of memory alignment: If a pointer pointing to 2 bytes/4
bytes is used to access the peripheral space, make sure the address is 2-byte/4-byte
aligned to avoid data read/write error. The following shows two incorrect formats:
u16 x = *(volatile u16*)0x808001; // 0x808001 is not 2-byte aligned
*(volatile u32*)0x808005 = 0x12345678; // 0x808005 is not 4-byte aligned
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