Raspberry Pi RP2040 User Manual (English)

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20: UART1 TX

21: UART1 RX

There is one line in the

setup_default_uart function:

bi_decl_if_func_used(bi_2pins_with_func(PICO_DEFAULT_UART_RX_PIN, PICO_DEFAULT_UART_TX_PIN,

GPIO_FUNC_UART));

The two pin numbers, and the function UART are stored, then decoded to their actual function names (UART1 TX etc) by

picotool. The

bi_decl_if_func_used makes sure the binary information is only included if the containing function is called.

Equally, the video code contains a few lines like this:

bi_decl_if_func_used(bi_pin_mask_with_name(0x1f << (PICO_SCANVIDEO_COLOR_PIN_BASE +

PICO_SCANVIDEO_DPI_PIXEL_RSHIFT),

"Red 0-4"));

Details

Things are designed to waste as little space as possible, but you can turn everything off with preprocessor var

PICO_NO_BINARY_INFO=1. Additionally any SDK code that inserts binary info can be separately excluded by its own

preprocesor var.

You need,

#include "pico/binary_info.h"

There are a bunch of bi_ macros in the headers

#define bi_binary_end(end)

#define bi_program_name(name)

#define bi_program_description(description)

#define bi_program_version_string(version_string)

#define bi_program_build_date_string(date_string)

#define bi_program_url(url)

#define bi_program_feature(feature)

#define bi_program_build_attribute(attr)

#define bi_1pin_with_func(p0, func)

#define bi_2pins_with_func(p0, p1, func)

#define bi_3pins_with_func(p0, p1, p2, func)

#define bi_4pins_with_func(p0, p1, p2, p3, func)

#define bi_5pins_with_func(p0, p1, p2, p3, p4, func)

#define bi_pin_range_with_func(plo, phi, func)

#define bi_pin_mask_with_name(pmask, label)

#define bi_pin_mask_with_names(pmask, label)

#define bi_1pin_with_name(p0, name)

#define bi_2pins_with_names(p0, name0, p1, name1)

#define bi_3pins_with_names(p0, name0, p1, name1, p2, name2)

#define bi_4pins_with_names(p0, name0, p1, name1, p2, name2, p3, name3)

which make use of underlying macros, e.g.

Getting started with Raspberry Pi Pico

Binary Information 71

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Raspberry Pi RP2040 Specifications

General

Processor	Dual-core Arm Cortex-M0+
Clock Speed	133 MHz
SRAM	264 KB
GPIO	30
USB	USB 1.1 Host/Device
PWM	16 channels
UART	2
SPI	2
I2C	2
Temperature Range	-20°C to +85°C
Operating Voltage	1.8V to 3.3V
Flash	External QSPI flash
I/O Interfaces	SPI, I2C, UART, PWM
ADC	4 × 12-bit ADC channels