Use the Programming bit in the Main Control Register (see Main Control Register, ETMCR) to disable all operations during programming.

When the Programming bit is set to 0 you must not write to registers other than the Main Control Register, because this can lead to Unpredictable behavior.

When setting the Programming bit, you must not change any other bits of the Main Control Register. You must only change the value of bits other than the Programming bit of the Control Register when bit [1] of the Status Register is set to 1. ARM recommends that you use a read-modify-write procedure when changing the Main Control Register.

When the Programming bit is set to 1:

Figure 2.1 shows a flow diagram of the procedure to program the PTM-A9 registers.