c - MSP430 Ram Overflow -

-

the msp430g2553 has 512 bytes of ram 16kb of flash memory. on microcontroller, static/global variables assigned in ram under .bss section. local variables assigned in ram under .stack section. dynamically allocated memory variables (malloc) assigned in ram under .sysmem section.

i have need msp430 keep track of connected devices via wifi. have struct such:

struct dev {     char type[20];     char ipaddress[13];     char name[20];     char status[1]; };

this struct takes 54 bytes of memory each device. planning on having 20+ devices connected msp430 , need have 20 of these structs. 20 x 54 bytes = 1080 bytes. big 512 bytes of ram.

is there way write these structs flash since have 16kb of memory use? understanding of flash variables read-only. these structs getting assigned read-write , not sure if possible.

i don't quite understand why ti make device has 16 kb flash , 512 bytes of ram, when variables requiring read-write operations stored in ram. seems waste of space.

i have tried change these sections .bss/.stack/.sysmem flash in linker file , msp430 not run this. have tried change size of ram , in linker file , change memory locations adding 512 bytes, not run either.

do have options here?

yes, can write data flash memory. problem arises when want change data. can erase sectors, have size of 512 bytes. take 2 flash sectors flash , store data 10 devices in each sector. flash can read ram though, don't need kind of swapping code, address each device entry pointer. last problem flash memory has limit of erase cycles, here around 10000 cycles. might have write code distribute data different sectors on time, depending on amount of expected changes , desired service durability.


Comments

Post a Comment

Popular posts from this blog

python - pip install -U PySide error -

-
does know how avoid following error when running pip install -u pyside per official website instructions here: https://pypi.python.org/pypi/pyside/#installing-pyside-on-a-mac-os-x-system note have done brew install qt successfully. you using pip version 7.0.3, version 7.1.2 available. should consider upgrading via 'pip install --upgrade pip' command. collecting pyside using cached pyside-1.2.4.tar.gz installing collected packages: pyside running setup.py install pyside complete output command /applications/anaconda/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/dy/ttgqhqqx3g9bsbsnqnxsk2z80000gq/t/pip-build-cpxemt/pyside/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/dy/ttgqhqqx3g9bsbsnqnxsk2z80000gq/t/pip-0r7hri-record/install-record.txt --single-version-externally-managed --compile:
Read more

arrays - C++ error: a brace-enclosed initializer is not allowed here before ‘{’ token -

-
simple question: i'm trying initialize array within c++ class declaration: using namespace std; #include <string> class myclass{ public: string myarray[] = {"a","b","c"}; }; and i'm getting error: error: brace-enclosed initializer not allowed here before ‘{’ token no, without complied c++11 compiler, cannot initialize member array in declaration. have initialize array member in constructor. , don't use open array if know number of elements initialize array.
Read more

cytoscape.js - How to add nodes to Dagre layout with Cytoscape -

-
i trying add nodes dagre graph through cityscape.js. problem nodes not painted. code have: cy.add({ group: "nodes", data: { id:"n0",name:"n0",weight: 75 }, }); $.ajax(url).done(function(jsontree){ var newnodes=[]; for(var i=1;i<6;i++){ //var child = jsontree.result[i]; newnodes.push( { group: "nodes", data: { id: "n"+i, name:"n"+i}}, { group: "edges", data: { id: "e"+i, source: "n0", target: "n"+i } } ); } cy.add(newnodes); any ideas? have used loaded function reload graph not work. not know if have use specific function reload graph. thank in advance. you need add positions new nodes. cytoscape.js docs : it important note positions of newly added nodes must defined when calling cy.add(). nodes can not placed in graph without valid position — otherwise not displayed. yo
Read more