SPRUJ79 November 2024 F29H850TU , F29H859TU-Q1
Test modes can be used for implementing diagnostics tests on memory controllers. These modes enable error injection in data and ECC. The memory controller supports three modes of operation:
In mode 2, only 32-bit reads are supported. The ECC bits appear in byte 0 position of the read data.
The following is an example sequence to inject faults into RAM to implement diagnostics tests:
ECC checks are performed in the CPU. CPU has built-in self-test controller and fault emulation to implement diagnostics. The MEMSS test mode is to implement diagnostic tests on ECC logic used for read-modify-write operations local to the memory controller.
The test mode can be enabled by CPU1 code running from LINK0, LINK1, and LINK2. RAM test mode takes effect only for CPU1 accesses. Accesses from other initiators are serviced in the normal mode of operation, irrespective of the RAM test mode setting. Implementing ECC diagnostics for read-modify-write from CPU1 is sufficient since ECC checking logic is common for all initiators. A software handshake can be implemented in case RAM diagnostics are run on shared memory addresses.
Real-time interrupts can still be enabled during diagnostics. In this scenario, an atomic sequence can be used to make sure the real-time interrupt is taken only after the dataline buffer is enabled and RAM is configured to mode 0.