MSP432E401Y: Passing the address of a CCS variable to inline assembly code

Hello Charles,

I'm using assembly because it's the only way I know to get data out of the eeprom on my board and, as I realized from the last project, I need to set the IP address ui32IPAddr, and Gateway address ui32GWAddr, when I initialize the board to use a static IP address. 

I'm looking at examples 6.3 and 6.4 and not having much luck. I was able to define the variable, var, as shown in example 6.3 and I was able to declare it to be external as shown in example 6.4, but I don't see any way to use it in an assm command in order to use it to get the data I need.  For example, if I try to use it in this command:

   mov   r1,var

I get a compilation error "Invalid operand".  Section 5.8 only confused me more.

Do you see what I'm doing wrong?

Thank you.

Brad McMillan said:

I'm using assembly because it's the only way I know to get data out of the eeprom on my board and, as I realized from the last project,

How did you program EEprom? To read EEprom, it is just a matter of calling EEPROMRead() and the data is saved on a variable.  See below example documented in the Peripheral Driver Library User's Guide. 

uint32_t ui32EEPROMInit;
uint32_t pui32Data[2];
uint32_t pui32Read[2];
//
// Enable the EEPROM module.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_EEPROM0);
//
// Wait for the EEPROM module to be ready.
//
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_EEPROM0))
{
}
//
// Wait for the EEPROM Initialization to complete
//
ui32EEPROMInit = EEPROMInit();
//
// Check if the EEPROM Initialization returned an error
// and inform the application
//
if(ui32EEPROMInit != EEPROM_INIT_OK)
{
while(1)
{
}
}
//
// Program some data into the EEPROM at address 0x400.
//
pui32Data[0] = 0x12345678;
pui32Data[1] = 0x56789abc;
EEPROMProgram(pui32Data, 0x400, sizeof(pui32Data));
//
// Read it back.
//
EEPROMRead(pui32Read, 0x400, sizeof(pui32Read));
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Hello Charles,

I got it working with one little problem. The IP address (192.168.1.101) I'm getting in pui32Read[0] is 0x6501A8C0, but I need the bytes reversed to be 0xC0A80165.  I know I can do this with a bunch of instructions, but I'm wondering if there is a simple C/C++ command to do this.

I'm still interested in any information I can get about how to pass variables back and forth between the C/C++ code and the assembly code because I'm sure I'll run into this problem again some time.

Thank you

Hello Charles,

The htonl() function worked, and now the EEPROMRead() function you posted above is working perfectly.

I really appreciate all the help.

Thank you so much.