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Add SPI support for RP2
Also add a sample code, `spi_flash.erl` confirmed to work on both Pico-W and ESP32C2, using the same high level SPI API. Signed-off-by: Paul Guyot <pguyot@kallisys.net>
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‎examples/erlang/CMakeLists.txt‎

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@@ -42,3 +42,4 @@ pack_runnable(network_console network_console estdlib eavmlib alisp)
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pack_runnable(logging_example logging_example estdlib eavmlib)
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pack_runnable(http_client http_client estdlib eavmlib avm_network)
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pack_runnable(disterl disterl estdlib)
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pack_runnable(spi_flash spi_flash eavmlib estdlib)

‎examples/erlang/rp2/CMakeLists.txt‎

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@@ -27,6 +27,17 @@ pack_uf2(pico_blink pico_blink)
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pack_uf2(pico_i2c_scanner pico_i2c_scanner)
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pack_uf2(pico_lis3dh pico_lis3dh)
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pack_uf2(pico_rtc pico_rtc)
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set(SPI_FLASH_AVM ${CMAKE_BINARY_DIR}/examples/erlang/spi_flash.avm)
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add_custom_command(
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OUTPUT spi_flash.uf2
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DEPENDS ${SPI_FLASH_AVM} UF2Tool
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COMMAND ${CMAKE_BINARY_DIR}/tools/uf2tool/uf2tool create -o spi_flash.uf2 -f universal -s 0x10180000 ${SPI_FLASH_AVM}
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COMMENT "Creating UF2 file spi_flash.uf2"
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VERBATIM
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)
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add_custom_target(spi_flash_uf2 ALL DEPENDS spi_flash.uf2)
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add_dependencies(spi_flash_uf2 spi_flash)
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pack_uf2(picow_blink picow_blink)
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pack_uf2(picow_wifi_sta picow_wifi_sta)
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pack_uf2(picow_wifi_ap picow_wifi_ap)

‎examples/erlang/spi_flash.erl‎

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@@ -0,0 +1,135 @@
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%
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% This file is part of AtomVM.
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%
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% Copyright 2026 Paul Guyot <pguyot@kallisys.net>
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%
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% Licensed under the Apache License, Version 2.0 (the "License");
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% you may not use this file except in compliance with the License.
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% You may obtain a copy of the License at
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%
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% http://www.apache.org/licenses/LICENSE-2.0
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%
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% Unless required by applicable law or agreed to in writing, software
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% distributed under the License is distributed on an "AS IS" BASIS,
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% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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% See the License for the specific language governing permissions and
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% limitations under the License.
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%
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% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
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%
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%%-----------------------------------------------------------------------------
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%% @doc SPI flash JEDEC ID reader example.
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%%
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%% Reads the JEDEC ID and Status Register 1 from a standard SPI flash chip
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%% (W25Qxx or similar) and prints the results every 5 seconds.
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%%
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%% Default pins are auto-detected from the platform and chip model:
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%%
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%% Pico (SPI0): SCK=GP2, MOSI=GP3, MISO=GP4, CS=GP5
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%% ESP32/S2/S3 (SPI2): SCK=18, MOSI=23, MISO=19, CS=5
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%% ESP32-C2/C3/C5 (SPI2): SCK=6, MOSI=7, MISO=2, CS=10
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%% ESP32-C6/C61 (SPI2): SCK=6, MOSI=7, MISO=2, CS=16
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%%
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%% Note: some breakout boards label pins using QSPI convention where
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%% D0 is MISO and D1 is MOSI (opposite of DI/DO). If you read all
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%% zeros, try swapping D0 and D1.
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%%
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%% The flash command byte is sent as the "address" parameter of read_at/4,
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%% using address_len_bits => 8 and command_len_bits => 0.
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%% @end
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%%-----------------------------------------------------------------------------
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-module(spi_flash).
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-export([start/0]).
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%% SPI flash commands
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-define(CMD_JEDEC_ID, 16#9F).
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-define(CMD_READ_STATUS1, 16#05).
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start() ->
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{SCK, MOSI, MISO, CS} = default_pins(),
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SPI = spi:open([
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{bus_config, [
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{sclk, SCK},
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{mosi, MOSI},
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{miso, MISO}
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]},
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{device_config, [
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{flash, [
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{cs, CS},
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{clock_speed_hz, 1000000},
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{mode, 0},
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{address_len_bits, 8},
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{command_len_bits, 0}
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]}
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]}
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]),
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loop(SPI).
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loop(SPI) ->
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read_jedec_id(SPI),
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read_status(SPI),
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timer:sleep(5000),
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loop(SPI).
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read_jedec_id(SPI) ->
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case spi:read_at(SPI, flash, ?CMD_JEDEC_ID, 24) of
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{ok, Value} ->
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Manufacturer = (Value bsr 16) band 16#FF,
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MemType = (Value bsr 8) band 16#FF,
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Capacity = Value band 16#FF,
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io:format(
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"JEDEC ID: manufacturer=0x~2.16.0B mem_type=0x~2.16.0B capacity=0x~2.16.0B~n", [
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Manufacturer, MemType, Capacity
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]
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),
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case manufacturer_name(Manufacturer) of
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unknown -> ok;
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Name -> io:format(" Manufacturer: ~s~n", [Name])
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end;
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{error, Reason} ->
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io:format("JEDEC ID read error: ~p~n", [Reason])
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end.
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read_status(SPI) ->
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case spi:read_at(SPI, flash, ?CMD_READ_STATUS1, 8) of
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{ok, Status} ->
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Busy = Status band 1,
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Wel = (Status bsr 1) band 1,
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io:format("Status Register 1: 0x~2.16.0B (BUSY=~B WEL=~B)~n", [
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Status, Busy, Wel
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]);
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{error, Reason} ->
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io:format("Status read error: ~p~n", [Reason])
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end.
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default_pins() ->
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default_pins(atomvm:platform()).
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%% {SCK, MOSI, MISO, CS}
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default_pins(pico) -> {2, 3, 4, 5};
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default_pins(esp32) -> esp32_default_pins().
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esp32_default_pins() ->
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#{model := Model} = erlang:system_info(esp32_chip_info),
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esp32_default_pins(Model).
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%% {SCK, MOSI, MISO, CS}
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esp32_default_pins(esp32) -> {18, 23, 19, 5};
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esp32_default_pins(esp32_s2) -> {18, 23, 19, 5};
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esp32_default_pins(esp32_s3) -> {18, 23, 19, 5};
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esp32_default_pins(esp32_c2) -> {6, 7, 2, 10};
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esp32_default_pins(esp32_c3) -> {6, 7, 2, 10};
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esp32_default_pins(esp32_c5) -> {6, 7, 2, 10};
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esp32_default_pins(esp32_c6) -> {6, 7, 2, 16};
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esp32_default_pins(esp32_c61) -> {6, 7, 2, 16};
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esp32_default_pins(_) -> {18, 23, 19, 5}.
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manufacturer_name(16#EF) -> "Winbond";
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manufacturer_name(16#C8) -> "GigaDevice";
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manufacturer_name(16#20) -> "Micron";
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manufacturer_name(16#01) -> "Spansion/Cypress";
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manufacturer_name(16#1F) -> "Adesto/Atmel";
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manufacturer_name(16#BF) -> "Microchip/SST";
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manufacturer_name(16#9D) -> "ISSI";
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manufacturer_name(_) -> unknown.

‎libs/avm_rp2/src/CMakeLists.txt‎

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@@ -26,6 +26,7 @@ set(ERLANG_MODULES
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gpio
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i2c
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pico
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spi
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)
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pack_archive(avm_rp2 DEPENDS_ON eavmlib ERLC_FLAGS +warnings_as_errors MODULES ${ERLANG_MODULES})

‎src/platforms/rp2/src/lib/CMakeLists.txt‎

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@@ -32,6 +32,7 @@ set(HEADER_FILES
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set(SOURCE_FILES
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gpiodriver.c
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i2cdriver.c
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spidriver.c
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networkdriver.c
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otp_crypto_platform.c
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platform_defaultatoms.c
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PUBLIC
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hardware_gpio
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hardware_i2c
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hardware_spi
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hardware_sync
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pico_float
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pico_mbedtls
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target_link_options(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC "SHELL:-Wl,-u -Wl,jit_stream_flash_get_nif")
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endif()
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target_link_options(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC "SHELL:-Wl,-u -Wl,gpio_nif -Wl,-u -Wl,i2c_nif -Wl,-u -Wl,otp_crypto_nif")
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target_link_options(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC "SHELL:-Wl,-u -Wl,gpio_nif -Wl,-u -Wl,i2c_nif -Wl,-u -Wl,spi_nif -Wl,-u -Wl,otp_crypto_nif")

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