ATG Debug Watchdog Hang - 1.0 English

ATG expects the application interface to accept a command within a certain wait time. ATG also looks for the application interface to return data within a certain wait time after a read command is issued. If either case is violated, ATG flags a Watchdog Hang.

When WatchDogHang is asserted, if vio_tg_status_state is in “*Wait” states, ATG is waiting for read data return. If vio_tg_status_state is in “Exe” state, ATG is waiting for the application interface to accept the next command.

Example 3: The following example shows that ATG asserts WatchDogHang. This example shares the same VIO control setting as Example 2. In this example, ATG vio_tg_status_state shows a “DNWait” state. Hence, ATG is waiting for read data return.

To further debug, vio_tg_instr_data_mode is updated to Linear data for better understanding in data return sequence.

.vio_tg_err_chk_en                  (1'b0), // Powers on Error Type Check
.vio_tg_direct_instr_en             (1'b1), // Powers on Direct Instruction Mode
.vio_tg_instr_num                   (5'b00000),
.vio_tg_instr_addr_mode             (TG_PATTERN_MODE_LINEAR),
.vio_tg_instr_data_mode             (TG_PATTERN_MODE_LINEAR),
.vio_tg_instr_rw_mode               (TG_RW_MODE_WRITE_READ),
.vio_tg_instr_rw_submode            (2'b00),
.vio_tg_instr_victim_mode           (TG_VICTIM_MODE_NO_VICTIM),
.vio_tg_instr_victim_select         (3'b000),
.vio_tg_instr_victim_aggr_delay     (5'd0),
.vio_tg_instr_num_of_iter           (32'd1000),
.vio_tg_instr_m_nops_btw_n_burst_m  (10'd0),
.vio_tg_instr_m_nops_btw_n_burst_n  (32'd10),
.vio_tg_instr_nxt_instr             (6’d0),

With Linear data, the following figure shows that when an error is detected, read data (vio_tg_status_read_bit) is one request ahead of expected data (vio_tg_status_exp_bit). One possibility is read command with address 0x1B0 is dropped. Hence, the next returned data with read address 0x1B8 is being compared against the expected data of read address 0x1B0.