I was programming and debugging code on a MSP430FR5736 over the past few days and then this morning started again and found that I got the message that security fuse flown or device not recognised. In the log it said security fuse blown. I have looked back through previous post but could find nothing that helped. I am using MSP-430UIF and IAR assembler. I have a MSP-TS430PW28 board and then my target board. I do not have an external power supply. I have check continuity between the TS430PW28 and the MCU and all is fine. I am using SBW to program. I erase main memory only, but have also treid erasing info memory as well. I have tried a number of boards. It seems they program the first time but not the second. It is as though I am blowing the fuse, or creating a condition that simulates this. I have 3.28V on Vcc. I have no shorts between any of the 4 pins. I have a pull up resistor for RST.
Any suggestions would be appreciated as I do not want to blow up any more.
Thanks
Peter