See comments below. On Tue, Apr 4, 2023 at 6:52 PM Bo Berglund via fpc-pascal < fpc-pascal@lists.freepascal.org> wrote:
> I use the method: > > i2cMaster.WriteBytesToReg(i2caddress: byte; regAddress: uint16; data: > PByte; > size: byte): boolean;) > > With data specified as follows in the call: > > if not i2cMaster.WriteBytesToReg(FEEPROMAddr, startaddress, @source[0], > NumBytes) then > > Here the source argument is a TBytes array of bytes so I supply the > address of > element 0 as the data argument (expected to be a PByte). > This is the correct way of passing the starting address of your data buffer. Is your startaddress variable an unsigned 16 bit integer (word/uint16)? If not, type cast this to a uint16 to ensure the compiler calls the correct overloaded method. > When I step through this in the debugger and get into the method itself I > can > see that the source argument contains the data I have loaded into it, so > the > data is there. > > When I run that method to the end and it finishes without error, I still > cannot > see the data in the EEPROM at the given address. > > So for testing I changed the call to be: > if not i2cMaster.WriteByteToReg(FEEPROMAddr, startaddress, source[0]) then > > This uses the method to write a single byte to the i2c device and it works > just > fine! > > So either there is a problem with the WriteBytesToReg() method or else my > use of > it... > Note that I haven't tested WriteByteToReg with a device supporting 10 bit register addresses, or in your case 16 bit... > What comes to mind is the data type PByte, which I have never used before > and do > not know if it is valid. > PByte is a pointer to a byte. > I am keeping the data in a dynamic array of bytes (the pascal type TBytes) > and > send the address of element 0 of that array as the argument to the method. > Is this wrong? > Passing the address of the first element of a TBytes array as you did above is correct. If so what should I use instead? > Can I typecast it like this: > > if not i2cMaster.WriteBytesToReg(FEEPROMAddr, startaddress, PByte(source), > NumBytes) then > (Tried it and it does not work) > No, this does not take the address of source, which is waht is required. > ???? > > Seems like I am getting close but missing something important... > I will look at the EEPROM datasheet, in case the details do not agree with the WriteBytesToReg implementation.
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