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Correct RSSI monitor busy and liveness timing #1454

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Correct RSSI monitor busy and liveness timing #1454

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dd0ba0b
fix(rssi): correct monitor busy and liveness timing
bengineerd Jul 7, 2026
14e97f0
Merge remote-tracking branch 'origin/rssi-regression-foundation' into…
bengineerd Jul 7, 2026
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21 changes: 15 additions & 6 deletions protocols/rssi/v1/rtl/RssiMonitor.vhd
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Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,8 @@ entity RssiMonitor is
STATUS_WIDTH_G : positive := 8;
CNT_WIDTH_G : positive := 32;
RETRANSMIT_ENABLE_G : boolean := true
--
);
--
);
port (
clk_i : in sl;
rst_i : in sl;
Expand Down Expand Up @@ -185,7 +185,9 @@ architecture rtl of RssiMonitor is
signal rin : RegType;
signal s_status : slv(STATUS_WIDTH_G - 1 downto 0);
--

begin

-- Status assignment
s_status(0) <= r.retransMax and r.sndResend and not r.sndResendD1;
s_status(1) <= r.nullTout;
Expand Down Expand Up @@ -312,8 +314,6 @@ begin
if (connActive_i = '0' or
(rxValid_i = '1' and rxFlags_i.data = '1') or
(rxValid_i = '1' and rxFlags_i.nul = '1') or
(rxValid_i = '1' and rxFlags_i.ack = '1') or
(rxValid_i = '1' and rxFlags_i.busy = '1') or
RETRANSMIT_ENABLE_G = false -- Disable null timeout
) then
v.nullToutCnt := (others => '0');
Expand Down Expand Up @@ -356,7 +356,7 @@ begin
dataHeadSt_i = '1' or
rstHeadSt_i = '1' or
nullHeadSt_i = '1' or
(rxLastSeqN_i - r.lastAckSeqN) = 0
((rxLastSeqN_i - r.lastAckSeqN) = 0 and localBusy_i = '0')
) then
v.ackToutCnt := (others => '0');
elsif ((rxLastSeqN_i - r.lastAckSeqN) > 0 and (rxLastSeqN_i - r.lastAckSeqN) <= rxWindowSize_i) or (localBusy_i = '1') then
Expand All @@ -374,8 +374,16 @@ begin
) then
v.sndAck := '0';

-- Periodic BUSY acknowledgment request. The RSSI page recommends
-- Retransmission Timeout/2 so the peer keeps its retransmission timer
-- reset while this receiver remains busy.
elsif (localBusy_i = '1' and (rxLastSeqN_i - r.lastAckSeqN) = 0 and
r.ackToutCnt >= ((conv_integer(rssiParam_i.retransTout)*SAMPLES_PER_TIME_C)/2)) then
v.sndAck := '1';

-- Timeout acknowledgment request
elsif (r.ackToutCnt >= (conv_integer(rssiParam_i.cumulAckTout)* SAMPLES_PER_TIME_C)) then
elsif ((rxLastSeqN_i - r.lastAckSeqN) > 0 and
r.ackToutCnt >= (conv_integer(rssiParam_i.cumulAckTout)* SAMPLES_PER_TIME_C)) then
v.sndAck := '1';

-- Cumulative acknowledgment request
Expand Down Expand Up @@ -460,4 +468,5 @@ begin
resendCnt_o <= r.resendCnt;
reconCnt_o <= r.reconCnt;
---------------------------------------------------------------------

end architecture rtl;
5 changes: 1 addition & 4 deletions tests/protocols/rssi/test_RssiMonitor.py
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@
from cocotb.clock import Clock
from cocotb.triggers import RisingEdge, Timer

from tests.common.regression_utils import env_flag, run_surf_vhdl_test
from tests.common.regression_utils import run_surf_vhdl_test


class TB:
Expand Down Expand Up @@ -222,10 +222,7 @@ async def local_busy_generates_periodic_ack_after_cumulative_timeout_test(dut):

PARAMETER_SWEEP = [pytest.param({}, id="server_monitor")]

KNOWN_ISSUE_REASON = "set RUN_RSSI_KNOWN_ISSUE_TESTS=1 to run RSSI cases that require follow-up RTL fixes"


@pytest.mark.skipif(not env_flag("RUN_RSSI_KNOWN_ISSUE_TESTS", default=False), reason=KNOWN_ISSUE_REASON)
@pytest.mark.parametrize("parameters", PARAMETER_SWEEP)
def test_RssiMonitor(parameters):
run_surf_vhdl_test(
Expand Down