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updated doc
This commit is contained in:
Peter Andersson
+141
-126
@@ -1,3 +1,131 @@
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* QUICK AND DIRTY INTEGRATION EXAMPLE
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So, assume you're running a Cortex-M3 board with a 2 MB SPI flash on it. The
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SPI flash has 64kB blocks. Your project is built using gnumake, and now you
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want to try things out.
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First, you simply copy the files in src/ to your own source folder. Exclude
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all files in test folder. Then you point out these files in your make script
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for compilation.
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Also copy the spiffs_config.h over from the src/default/ folder.
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Try building. This fails, nagging about inclusions and u32_t and whatnot. Open
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the spiffs_config.h and delete the bad inclusions. Also, add following
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typedefs:
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typedef signed int s32_t;
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typedef unsigned int u32_t;
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typedef signed short s16_t;
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typedef unsigned short u16_t;
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typedef signed char s8_t;
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typedef unsigned char u8_t;
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Now it should build. Over to the mounting business. Assume you already
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implemented the read, write and erase functions to your SPI flash:
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void my_spi_read(int addr, int size, char *buf)
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void my_spi_write(int addr, int size, char *buf)
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void my_spi_erase(int addr, int size)
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In your main.c or similar, include the spiffs.h and do that spiffs struct:
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#include <spiffs.h>
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static spiffs fs;
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Also, toss up some of the needed buffers:
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#define LOG_PAGE_SIZE 256
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static u8_t spiffs_work_buf[LOG_PAGE_SIZE*2];
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static u8_t spiffs_fds[32*4];
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static u8_t spiffs_cache[(LOG_PAGE_SIZE+32)*4];
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Now, write the my_spiffs_mount function:
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void my_spiffs_mount() {
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spiffs_config cfg;
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cfg.phys_size = 2*1024*1024; // use all spi flash
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cfg.phys_addr = 0; // start spiffs at start of spi flash
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cfg.phys_erase_block = 65536; // according to datasheet
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cfg.log_block_size = 65536; // let us not complicate things
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cfg.log_block_size = LOG_PAGE_SIZE; // as we said
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cfg.hal_read_f = my_spi_read;
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cfg.hal_write_f = my_spi_write;
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cfg.hal_erase_f = my_spi_erase;
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int res = SPIFFS_mount(&fs,
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&cfg,
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spiffs_work_buf,
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spiffs_fds,
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sizeof(spiffs_fds),
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spiffs_cache,
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sizeof(spiffs_cache),
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0);
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printf("mount res: %i\n", res);
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}
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Now, build warns about the my_spi_read, write and erase functions. Wrong
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signatures, so go wrap them:
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static s32_t my_spiffs_read(u32_t addr, u32_t size, u8_t *dst) {
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my_spi_read(addr, size, dst);
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return SPIFFS_OK;
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}
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static s32_t my_spiffs_write(u32_t addr, u32_t size, u8_t *src) {
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my_spi_write(addr, size, dst);
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return SPIFFS_OK;
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}
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static s32_t my_spiffs_erase(u32_t addr, u32_t size) {
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my_spi_erase(addr, size);
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return SPIFFS_OK;
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}
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Redirect the config in my_spiffs_mount to the wrappers instead:
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cfg.hal_read_f = my_spiffs_read;
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cfg.hal_write_f = my_spiffs_write;
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cfg.hal_erase_f = my_spiffs_erase;
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Ok, now you should be able to build and run. However, you get this output:
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mount res: -1
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but you wanted
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mount res: 0
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This is probably due to you having experimented with your SPI flash, so it
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contains rubbish from spiffs's point of view. Do a mass erase and run again.
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If all is ok now, you're good to go. Try creating a file and read it back:
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static void test_spiffs() {
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char buf[12];
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// Surely, I've mounted spiffs before entering here
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spiffs_file fd = SPIFFS_open(&fs, "my_file", SPIFFS_CREAT | SPIFFS_TRUNC | SPIFFS_RDWR, 0);
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if (SPIFFS_write(&fs, fd, (u8_t *)"Hello world", 12) < 0) printf("errno %i\n", SPIFFS_errno(&fs));
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SPIFFS_close(&fs, fd);
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fd = SPIFFS_open(&fs, "my_file", SPIFFS_RDWR, 0);
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if (SPIFFS_read(&fs, fd, (u8_t *)buf, 12) < 0) printf("errno %i\n", SPIFFS_errno(&fs));
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SPIFFS_close(&fs, fd);
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printf("--> %s <--\n", buf);
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}
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Compile, run, cross fingers hard, and you'll get the output:
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--> Hello world <--
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Got errors? Check spiffs.h for error definitions to get a clue what went voodoo.
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* INTEGRATING SPIFFS
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In order to integrate spiffs to your embedded target, you will basically need:
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@@ -129,139 +257,26 @@ logical page size. It also needs at least one file descriptor. If cache is
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enabled (highly recommended), it will also need a bunch of cache pages.
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Say you have a logical page size of 256 bytes. You want to be able to have four
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files open simultaneously, and you can give spiffs four cache pages. This sums
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up to:
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files open simultaneously, and you can give spiffs four cache pages. This
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roughly sums up to:
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256*2 (work buffer) + 32*4 (file descriptors) + (256+32)*4 cache pages
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i.e. 1792 bytes.
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256*2 (work buffer) +
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32*4 (file descriptors) +
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(256+32)*4 (cache pages) + 40 (cache metadata)
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i.e. 1832 bytes.
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This is apart from call stack usage.
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To get the exact amount of bytes needed on your specific target, enable
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SPIFFS_BUFFER_HELP in spiffs_config.h, rebuild and call:
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* QUICK AND DIRTY INTEGRATION EXAMPLE
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So, assume you're running a Cortex-M3 board with a 2 MB SPI flash on it. The
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SPI flash has 64kB blocks. Your project is built using gnumake, and now you
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want to try things out.
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First, you simply copy the files named in files.mk to your own source folder. Then
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you point out these files in your make script for compilation.
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Also copy the spiffs_config.h over from the default/ folder.
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Try building. This fails, nagging about inclusions and u32_t and whatnot. Open
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the spiffs_config.h and delete the bad inclusions. Also, add following
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typedefs:
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typedef signed int s32_t;
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typedef unsigned int u32_t;
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typedef signed short s16_t;
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typedef unsigned short u16_t;
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typedef signed char s8_t;
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typedef unsigned char u8_t;
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SPIFFS_buffer_bytes_for_filedescs
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SPIFFS_buffer_bytes_for_cache
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Now it should build. Over to the mounting business. Assume you already
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implemented the read, write and erase functions to your SPI flash:
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Having these figures you can disable SPIFFS_BUFFER_HELP again to save flash.
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void my_spi_read(int addr, int size, char *buf)
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void my_spi_write(int addr, int size, char *buf)
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void my_spi_erase(int addr, int size)
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In your main.c or similar, include the spiffs.h and do that spiffs struct:
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#include <spiffs.h>
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static spiffs fs;
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Also, toss up some of the needed buffers:
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#define LOG_PAGE_SIZE 256
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static u8_t spiffs_work_buf[LOG_PAGE_SIZE*2];
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static u8_t spiffs_fds[32*4];
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static u8_t spiffs_cache[(LOG_PAGE_SIZE+32)*4];
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Now, write the my_spiffs_mount function:
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void my_spiffs_mount() {
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spiffs_config cfg;
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cfg.phys_size = 2*1024*1024; // use all spi flash
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cfg.phys_addr = 0; // start spiffs at start of spi flash
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cfg.phys_erase_block = 65536; // according to datasheet
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cfg.log_block_size = 65536; // let us not complicate things
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cfg.log_block_size = LOG_PAGE_SIZE; // as we said
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cfg.hal_read_f = my_spi_read;
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cfg.hal_write_f = my_spi_write;
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cfg.hal_erase_f = my_spi_erase;
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int res = SPIFFS_mount(&fs,
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&cfg,
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spiffs_work_buf,
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spiffs_fds,
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sizeof(spiffs_fds),
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spiffs_cache,
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sizeof(spiffs_cache),
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0);
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printf("mount res: %i\n", res);
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}
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Now, build warns about the my_spi_read, write and erase functions. Wrong
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signatures, so go wrap them:
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static s32_t my_spiffs_read(u32_t addr, u32_t size, u8_t *dst) {
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my_spi_read(addr, size, dst);
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return SPIFFS_OK;
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}
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static s32_t my_spiffs_write(u32_t addr, u32_t size, u8_t *src) {
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my_spi_write(addr, size, dst);
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return SPIFFS_OK;
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}
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static s32_t my_spiffs_erase(u32_t addr, u32_t size) {
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my_spi_erase(addr, size);
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return SPIFFS_OK;
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}
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Redirect the config in my_spiffs_mount to the wrappers instead:
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cfg.hal_read_f = my_spiffs_read;
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cfg.hal_write_f = my_spiffs_write;
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cfg.hal_erase_f = my_spiffs_erase;
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Ok, now you should be able to build and run. However, you get this output:
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mount res: -1
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but you wanted
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mount res: 0
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This is probably due to you having being experimenting with your SPI flash, so
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it contains garbage from spiffs's point of view. Do a mass erase and run again.
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If all is ok now, you're good to go. Try creating a file and read it back:
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static void test_spiffs() {
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char buf[12];
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spiffs_file fd = SPIFFS_open(&fs, "my_file", 0, SPIFFS_CREAT | SPIFFS_TRUNC | SPIFFS_RDWR);
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if (SPIFFS_write(&fs, fd, "Hello world", 12) < 0) printf("errno %i\n", SPIFFS_errno(&fs));
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SPIFFS_close(&fs, fd);
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fd = SPIFFS_open(&fs, "my_file", 0, SPIFFS_RDWR);
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if (SPIFFS_read(&fs, fd, buf, 12) < 0) printf("errno %i\n", SPIFFS_errno(&fs));
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SPIFFS_close(&fs, fd);
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printf("--> %s <--\n", buf);
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}
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And, crossing fingers hard, you'll get the output:
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--> Hello world <--
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* HOW TO CONFIG
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TODO
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