PIC18 DataRAM 笔记

1.疑似最糟糕的英文技术文档段落

Since up to 16 registers may share the same low-order address, the user must always be careful to ensure that the proper bank is selected before performing a data read or write. For example, writing what should be program data to an 8-bit address of F9h while the BSR is 0Fh will end up resetting the program counter.

1.16(Bytes?) register mapped zone in lowest addr is different from each other in each bank。

 2.the example, if we write anything to 0f:00f9h in data ram, the program counter is reset?

3.who wrote this paragraph?????!!!! 

2.关键信息

12 Bits Address

Most Addr :4096Bytes.

16Bank(Bit4 higher)............256/perBank(0xff...Bit8 lower)

SFR is  chip register itself.

GPR is just Data RAM, it is static, which means it can tranfer infos from bootloader to App, vice vesa?

BSR is storage the most significant bits(4Bits) of the target addr.

MOVFF can hould the entire 12Bits addr of data ram.

SFR only located at F38~FFFh。 the F60~ FFFh is mapped to ACCESS Bank（"a"=0 is Access Bank mode;"a"=1  using BSR. the  256bytes accessable data RAM is all GPR, the SFR in higner address is Hiding in this mode）.这一段可是未明言For exmaple的事，可以推理的是，此时"a"=0,  BSR 仍然有用。在此时。

3.回顾最初的问题

1.low-order address has 8bits. equal to low bytes of data ram addr.

2.16 registers may share the  same address. the register is data ram byte itself, can be GPR, can be SFR.

3. BSR is important.(if you jump from one app to another).

4.the example,  that program conter register is PC register, which abs or full addr is 0xff9h.