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hello and welcome to controllers Tech
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this is the third video in The w25q
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Flash series and today we will cover how
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I planned this video to cover the right
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operation also but the video turned out
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very lengthy and therefore I have split
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them into two separate videos
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this video will cover how we enable and
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disable the right and how to erase a
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particular sector or number of sectors
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in the next video we will see how to
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perform the right operation on a page or
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this is the continuation from the
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previous video where we saw how to
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perform the read operation
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the data was stored at some particular
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locations but in different sectors
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as we will erase those particular
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sectors today let's quickly see the
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the first set of data is stored on page
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1 at an offset of 85.
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if we read the device starting from page
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0 we get the data at an offset of 341.
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there is another set of data located in
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another sector on page 17.
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let's see the data sheet now
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here is the sector arrays instruction
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along with sector arrays we can also
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perform 32 kilobytes or 64 kilobytes
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or erase the entire chip
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basically sector is the minimum memory
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segment that we can erase
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we cannot erase a single page or a
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if you want to update even a single byte
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of memory you need to erase the entire
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the sector arrays command erases the
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four kilobytes memory segment by setting
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but before performing the arrays we
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should first execute the right enable
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the method to send the instruction is
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the same we send the instruction
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followed by the 24-bit address
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let's see the right enable instruction
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the write enable instruction sets the
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right enable latch in the status
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this must be done before we perform a
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right operation the arrays operation or
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update security in status registers
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the instruction code is 6 hex
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let's write a new function write enable
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the procedure to send the instruction is
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we pull the Cs pin low
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send the instruction to the device
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let's give a small delay just to be safe
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just like write enable there is an
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instruction to disable the right
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the process is the same just the command
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now we have the right enable instruction
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so let's erase the sector
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the command is sent in the similar way
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we sent other commands
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pull the Cs pin low send the instruction
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along with the memory address and then
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let's write a function to erase the
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sector whose parameter will be the
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number of sector we want to erase
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Define the data array to be sent
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now calculate the memory address using
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each sector contains 16 pages and each
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page contains 256 bytes so the memory
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address will be sector number times 16
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now before we send the command enable
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the command is sent in the similar
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manner We performed the read operation
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the instruction to erase the sector is
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and we don't need to send the dummy
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after the data has been copied in the
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data array send the data to the SBI
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we need to send different number of
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after sending the command disable the
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if you check the AC Electrical
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characteristics of the device you can
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find the time requirement to perform
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for erasing the sector the maximum time
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required is 400 milliseconds
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let's give a delay of 450 milliseconds
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so this completes the sector arrays
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let's define it in the header file so
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that we can call it from the main file
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in the main file we read the data from
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two different locations and both were in
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we will read the data then erase the
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sector and then read the data again
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this will confirm whether the data was
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erased from the given location or not
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let's build and debug the code
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since we are reading data from the
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location where it is stored we will get
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the data in the beginning of the RX
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buffer all right let's run the code now
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here you can see we have received the
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data now run the sector arrays command
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and when we read the data again from the
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same location we get FF hex
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this means the data was erased from the
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first location actually the entire
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Now read the data from the second
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location which is in sector 1. here we
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Now erase sector 1. and when we read
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again the data is replaced with FF hex
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this data is permanently gone now
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if we reset the debugger and try to read
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the data again we will just find FFX at
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so we have successfully erased the first
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erasing a sector is necessary as I
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mentioned this is the minimum memory
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segment that we can erase
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when we perform the right operation we
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need to erase a sector before writing
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this is because the write can be only
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performed on those memory locations
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whose current value is FF hex
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if a memory location already has some
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data we cannot replace that data we have
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to first erase it and then write new
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we will cover the page right in the next
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video which will be out in three days
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this is it for this video
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I hope you understood how to erase a
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the link to download the code is in the
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description of the video
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leave comments in case of any doubt
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keep watching and have a nice day ahead
