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feat: hold the WiFi module in reset until enabled by the firmware (FPGA v8)

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randogoth 2026-10-25 16:13:29 +02:00
parent eaf8cd284a
commit 853addaa22
6 changed files with 24 additions and 9 deletions
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8
fpga/rtl/strix.v
View file

@ -34,6 +34,8 @@ module strix (
// NINA pass-through: the SAMD21 talks to the WiFi module as if wired directly.
wire nina_enable; // from strix_core
wire sam_nina_mosi = bMKR_D[8]; // SERCOM1
wire sam_nina_sck = bMKR_D[9];
wire sam_nina_ss = bMKR_D[5];
@ -45,7 +47,9 @@ module strix (
assign bWM_PIO29 = sam_nina_sck;
assign bWM_PIO28 = sam_nina_ss;
assign bWM_PIO27 = sam_nina_gpio0;
assign oWM_RESET = sam_nina_resetn;
// The module stays in reset until the firmware enables it: its boot current on top of the
// ring oscillators can brown out the board, and it is not needed without WiFi.
assign oWM_RESET = nina_enable ? sam_nina_resetn : 1'b0;
assign oWM_RX = sam_uart_tx;
assign bWM_PIO1 = 1'bz; // inputs from NINA
assign bWM_PIO7 = 1'bz;
@ -64,7 +68,7 @@ module strix (
strix_core core (
.clk(clk), .reset(reset),
.spi_sck(strix_sck), .spi_mosi(strix_mosi), .spi_ss_n(strix_ss_n),
.spi_miso(strix_miso), .capture_done(capture_done)
.spi_miso(strix_miso), .capture_done(capture_done), .nina_enable(nina_enable)
);
assign oSAM_INT = capture_done;

9
fpga/rtl/strix_core.v
View file

@ -36,10 +36,11 @@ module strix_core #(
input wire spi_mosi,
input wire spi_ss_n,
output wire spi_miso,
output wire capture_done
output wire capture_done,
output reg nina_enable // releases the WiFi module from reset (see REG_NINA_CTRL)
);
localparam [7:0] VERSION = 8'h07;
localparam [7:0] VERSION = 8'h08;
localparam GENERATORS = 4;
localparam [6:0] REG_ID0 = 7'h00, // "STRX"
@ -84,6 +85,7 @@ module strix_core #(
REG_LEVEL_LOW = 7'h2B,
REG_DROP_HIGH = 7'h2C, // bytes dropped because the FIFO was full
REG_DROP_LOW = 7'h2D,
REG_NINA_CTRL = 7'h2E, // bit 0: WiFi module may run (otherwise held in reset)
REG_STATS = 7'h40, // burst read of the statistics trial snapshot
REG_STREAM = 7'h44, // burst read of entropy bytes
REG_AMP = 7'h42, // burst read of the amplifier trial snapshot
@ -327,6 +329,7 @@ module strix_core #(
REG_LEVEL_LOW: tx_byte_next = stream_level[7:0];
REG_DROP_HIGH: tx_byte_next = stream_dropped[15:8];
REG_DROP_LOW: tx_byte_next = stream_dropped[7:0];
REG_NINA_CTRL: tx_byte_next = {7'd0, nina_enable};
REG_AMP_CTRL: tx_byte_next = {7'd0, amp_von_neumann};
REG_AMP_SOURCES: tx_byte_next = {4'd0, amp_sources};
REG_AMP_SUB_MS: tx_byte_next = amp_sub_ms;
@ -403,6 +406,7 @@ module strix_core #(
amp_stage_param <= {16'd4, 16'd8, 16'd8}; // random walk 8 x 8 x 4 = bound 256
amp_index <= 8'd0;
stream_source <= 3'd4;
nina_enable <= 1'b0;
stream_von_neumann <= 1'b0;
is_read <= 1'b0;
reg_addr <= 7'd0;
@ -450,6 +454,7 @@ module strix_core #(
REG_MAX_DEAD: max_dead <= rx_byte;
REG_TRIAL_HIGH: trial_ms[15:8] <= rx_byte;
REG_TRIAL_LOW: trial_ms[7:0] <= rx_byte;
REG_NINA_CTRL: nina_enable <= rx_byte[0];
REG_STREAM_CTRL: begin
if (rx_byte[2:0] <= 3'd4) stream_source <= rx_byte[2:0];
stream_von_neumann <= rx_byte[3];

2
fpga/sim/tb_strix_core.v
View file

@ -282,7 +282,7 @@ module tb_strix_core;
// Identification
read_reg(REG_ID0, v); expect(v, "S", "ID0");
read_reg(REG_ID3, v); expect(v, "X", "ID3");
read_reg(REG_VERSION, v); expect(v, 8'h07, "VERSION");
read_reg(REG_VERSION, v); expect(v, 8'h08, "VERSION");
read_reg(REG_GENERATORS, v); expect(v, 8'd4, "GENERATORS");
read_reg(REG_RINGS, v); expect(v, RINGS, "RINGS");
read_reg(REG_TEMPORAL, v); expect(v, 8'd5, "TEMPORAL");

5
fpga/src/strix.qsf
View file

@ -87,6 +87,11 @@ set_global_assignment -name CONFIGURATION_VCCIO_LEVEL AUTO
set_global_assignment -name ON_CHIP_BITSTREAM_DECOMPRESSION ON
set_global_assignment -name GENERATE_TTF_FILE ON
# Weak pull-ups keep the NINA module's SS and GPIO0 (boot mode) high while the SAMD21 leaves
# these pass-through pins floating. Its reset is gated in the FPGA (REG_NINA_CTRL).
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to bMKR_D[5]
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to bMKR_D[6]
set_location_assignment PIN_E2 -to iCLK
set_location_assignment PIN_E1 -to iRESETn
set_location_assignment PIN_E10 -to oSDRAM_ADDR[11]