1. A method, comprising: receiving control data; storing the control data in a control register; receiving an address, wherein the address is an address of a memory map of a data processing system; storing the address data in an address register; receiving a trigger in response to an event of a processing unit of the data processing system; determining to respond to the trigger based on the control data stored in the control register; determining a transaction to perform based on the control data stored in the control register; if the transaction includes a first type of transaction: writing first data to the address; determining to perform a first trace; and sending a first trace message that includes the first data; and if the transaction includes a second type of transaction: reading second data from the address; determining to perform a second trace; and sending a second trace message that includes the second data.