add docs for pio_instructions.h (#624)


Co-authored-by: Andrew Scheller <andrew.scheller@raspberrypi.com>
diff --git a/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h b/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h
index 07df65b..3662135 100644
--- a/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h
+++ b/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h
@@ -9,7 +9,18 @@
 
 #include "pico.h"
 
-// PICO_CONFIG: PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS, Enable/disable assertions in the PIO instructions, type=bool, default=0, group=hardware_pio
+/** \brief PIO instruction encoding 
+ *  \defgroup pio_instructions pio_instructions
+ *  \ingroup hardware_pio
+ * 
+ * Functions for generating PIO instruction encodings programmatically. In debug builds
+ *`PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS` can be set to 1 to enable validation of encoding function
+ * parameters.
+ *
+ * For fuller descriptions of the instructions in question see the "RP2040 Datasheet"
+ */
+
+// PICO_CONFIG: PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS, Enable/disable assertions in the PIO instructions, type=bool, default=0, group=pio_instructions
 #ifndef PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS
 #define PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS 0
 #endif
@@ -44,6 +55,12 @@
 #define _PIO_INVALID_MOV_DEST 0u
 #endif
 
+/*! \brief Enumeration of values to pass for source/destination args for instruction encoding functions
+ *  \ingroup pio_instructions
+ *
+ * \note Not all values are suitable for all functions. Validity is only checked in debug mode when
+ * `PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS` is 1
+ */
 enum pio_src_dest {
     pio_pins = 0u,
     pio_x = 1u,
@@ -58,11 +75,11 @@
     pio_exec_out = 7u | _PIO_INVALID_IN_SRC | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC | _PIO_INVALID_MOV_DEST,
 };
 
-inline static uint _pio_major_instr_bits(uint instr) {
+static inline uint _pio_major_instr_bits(uint instr) {
     return instr & 0xe000u;
 }
 
-inline static uint _pio_encode_instr_and_args(enum pio_instr_bits instr_bits, uint arg1, uint arg2) {
+static inline uint _pio_encode_instr_and_args(enum pio_instr_bits instr_bits, uint arg1, uint arg2) {
     valid_params_if(PIO_INSTRUCTIONS, arg1 <= 0x7);
 #if PARAM_ASSERTIONS_ENABLED(PIO_INSTRUCTIONS)
     uint32_t major = _pio_major_instr_bits(instr_bits);
@@ -75,100 +92,388 @@
     return instr_bits | (arg1 << 5u) | (arg2 & 0x1fu);
 }
 
-inline static uint _pio_encode_instr_and_src_dest(enum pio_instr_bits instr_bits, enum pio_src_dest dest, uint value) {
+static inline uint _pio_encode_instr_and_src_dest(enum pio_instr_bits instr_bits, enum pio_src_dest dest, uint value) {
     return _pio_encode_instr_and_args(instr_bits, dest & 7u, value);
 }
 
-inline static uint pio_encode_delay(uint cycles) {
+/*! \brief Encode just the delay slot bits of an instruction
+ *  \ingroup pio_instructions
+ *
+ * \note This function does not return a valid instruction encoding; instead it returns an encoding of the delay
+ * slot suitable for `OR`ing with the result of an encoding function for an actual instruction. Care should be taken when
+ * combining the results of this function with the results of \ref pio_encode_sideset and \ref pio_encode_sideset_opt
+ * as they share the same bits within the instruction encoding.
+ *
+ * \param cycles the number of cycles 0-31 (or less if side set is being used)
+ * \return the delay slot bits to be ORed with an instruction encoding
+ */
+static inline uint pio_encode_delay(uint cycles) {
     // note that the maximum cycles will be smaller if sideset_bit_count > 0
     valid_params_if(PIO_INSTRUCTIONS, cycles <= 0x1f);
     return cycles << 8u;
 }
 
-inline static uint pio_encode_sideset(uint sideset_bit_count, uint value) {
+/*! \brief Encode just the side set bits of an instruction (in non optional side set mode)
+ *  \ingroup pio_instructions
+ *
+ * \note This function does not return a valid instruction encoding; instead it returns an encoding of the side set bits
+ * suitable for `OR`ing with the result of an encoding function for an actual instruction. Care should be taken when
+ * combining the results of this function with the results of \ref pio_encode_delay as they share the same bits
+ * within the instruction encoding.
+ *
+ * \param sideset_bit_count number of side set bits as would be specified via `.sideset` in pioasm
+ * \param value the value to sideset on the pins
+ * \return the side set bits to be ORed with an instruction encoding
+ */
+static inline uint pio_encode_sideset(uint sideset_bit_count, uint value) {
     valid_params_if(PIO_INSTRUCTIONS, sideset_bit_count >= 1 && sideset_bit_count <= 5);
     valid_params_if(PIO_INSTRUCTIONS, value <= ((1u << sideset_bit_count) - 1));
     return value << (13u - sideset_bit_count);
 }
 
-inline static uint pio_encode_sideset_opt(uint sideset_bit_count, uint value) {
+/*! \brief Encode just the side set bits of an instruction (in optional -`opt` side set mode)
+ *  \ingroup pio_instructions
+ *
+ * \note This function does not return a valid instruction encoding; instead it returns an encoding of the side set bits
+ * suitable for `OR`ing with the result of an encoding function for an actual instruction. Care should be taken when
+ * combining the results of this function with the results of \ref pio_encode_delay as they share the same bits
+ * within the instruction encoding.
+ *
+ * \param sideset_bit_count number of side set bits as would be specified via `.sideset <n> opt` in pioasm
+ * \param value the value to sideset on the pins
+ * \return the side set bits to be ORed with an instruction encoding
+ */
+static inline uint pio_encode_sideset_opt(uint sideset_bit_count, uint value) {
     valid_params_if(PIO_INSTRUCTIONS, sideset_bit_count >= 1 && sideset_bit_count <= 4);
     valid_params_if(PIO_INSTRUCTIONS, value <= ((1u << sideset_bit_count) - 1));
     return 0x1000u | value << (12u - sideset_bit_count);
 }
 
-inline static uint pio_encode_jmp(uint addr) {
+/*! \brief Encode an unconditional JMP instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp(uint addr) {
     return _pio_encode_instr_and_args(pio_instr_bits_jmp, 0, addr);
 }
 
-inline static uint _pio_encode_irq(bool relative, uint irq) {
+/*! \brief Encode a conditional JMP if scratch X zero instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP !X <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_not_x(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 1, addr);
+}
+
+/*! \brief Encode a conditional JMP if scratch X non-zero (and post-decrement X) instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP X-- <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_x_dec(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 2, addr);
+}
+
+/*! \brief Encode a conditional JMP if scratch Y zero instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP !Y <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_not_y(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 3, addr);
+}
+
+/*! \brief Encode a conditional JMP if scratch Y non-zero (and post-decrement Y) instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP Y-- <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_y_dec(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 4, addr);
+}
+
+/*! \brief Encode a conditional JMP if scratch X not equal scratch Y instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP X!=Y <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_x_ne_y(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 5, addr);
+}
+
+/*! \brief Encode a conditional JMP if input pin high instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP PIN <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_pin(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 6, addr);
+}
+
+/*! \brief Encode a conditional JMP if output shift register not empty instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `JMP !OSRE <addr>`
+ *
+ * \param addr The target address 0-31 (an absolute address within the PIO instruction memory)
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_jmp_not_osre(uint addr) {
+    return _pio_encode_instr_and_args(pio_instr_bits_jmp, 7, addr);
+}
+
+static inline uint _pio_encode_irq(bool relative, uint irq) {
     valid_params_if(PIO_INSTRUCTIONS, irq <= 7);
     return (relative ? 0x10u : 0x0u) | irq;
 }
 
-inline static uint pio_encode_wait_gpio(bool polarity, uint pin) {
-    return _pio_encode_instr_and_args(pio_instr_bits_wait, 0u | (polarity ? 4u : 0u), pin);
+/*! \brief Encode a WAIT for GPIO pin instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `WAIT <polarity> GPIO <gpio>`
+ *
+ * \param polarity true for `WAIT 1`, false for `WAIT 0`
+ * \param gpio The real GPIO number 0-31
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_wait_gpio(bool polarity, uint gpio) {
+    return _pio_encode_instr_and_args(pio_instr_bits_wait, 0u | (polarity ? 4u : 0u), gpio);
 }
 
-inline static uint pio_encode_wait_pin(bool polarity, uint pin) {
+/*! \brief Encode a WAIT for pin instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `WAIT <polarity> PIN <pin>`
+ *
+ * \param polarity true for `WAIT 1`, false for `WAIT 0`
+ * \param pin The pin number 0-31 relative to the executing SM's input pin mapping
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_wait_pin(bool polarity, uint pin) {
     return _pio_encode_instr_and_args(pio_instr_bits_wait, 1u | (polarity ? 4u : 0u), pin);
 }
 
-inline static uint pio_encode_wait_irq(bool polarity, bool relative, uint irq) {
+/*! \brief Encode a WAIT for IRQ instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `WAIT <polarity> IRQ <irq> <relative>`
+ *
+ * \param polarity true for `WAIT 1`, false for `WAIT 0`
+ * \param relative true for a `WAIT IRQ <irq> REL`, false for regular `WAIT IRQ <irq>`
+ * \param irq the irq number 0-7
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_wait_irq(bool polarity, bool relative, uint irq) {
     valid_params_if(PIO_INSTRUCTIONS, irq <= 7);
     return _pio_encode_instr_and_args(pio_instr_bits_wait, 2u | (polarity ? 4u : 0u), _pio_encode_irq(relative, irq));
 }
 
-inline static uint pio_encode_in(enum pio_src_dest src, uint value) {
+/*! \brief Encode an IN instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `IN <src>, <count>`
+ *
+ * \param src The source to take data from
+ * \param count The number of bits 1-32
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_in(enum pio_src_dest src, uint count) {
     valid_params_if(PIO_INSTRUCTIONS, !(src & _PIO_INVALID_IN_SRC));
-    return _pio_encode_instr_and_src_dest(pio_instr_bits_in, src, value);
+    return _pio_encode_instr_and_src_dest(pio_instr_bits_in, src, count);
 }
 
-inline static uint pio_encode_out(enum pio_src_dest dest, uint value) {
+/*! \brief Encode an OUT instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `OUT <src>, <count>`
+ *
+ * \param dest The destination to write data to
+ * \param count The number of bits 1-32
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_out(enum pio_src_dest dest, uint count) {
     valid_params_if(PIO_INSTRUCTIONS, !(dest & _PIO_INVALID_OUT_DEST));
-    return _pio_encode_instr_and_src_dest(pio_instr_bits_out, dest, value);
+    return _pio_encode_instr_and_src_dest(pio_instr_bits_out, dest, count);
 }
 
-inline static uint pio_encode_push(bool if_full, bool block) {
+/*! \brief Encode a PUSH instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `PUSH <if_full>, <block>`
+ *
+ * \param if_full true for `PUSH IF_FULL ...`, false for `PUSH ...`
+ * \param block true for `PUSH ... BLOCK`, false for `PUSH ...`
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_push(bool if_full, bool block) {
     return _pio_encode_instr_and_args(pio_instr_bits_push, (if_full ? 2u : 0u) | (block ? 1u : 0u), 0);
 }
 
-inline static uint pio_encode_pull(bool if_empty, bool block) {
+/*! \brief Encode a PULL instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `PULL <if_empty>, <block>`
+ *
+ * \param if_empty true for `PULL IF_EMPTY ...`, false for `PULL ...`
+ * \param block true for `PULL ... BLOCK`, false for `PULL ...`
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_pull(bool if_empty, bool block) {
     return _pio_encode_instr_and_args(pio_instr_bits_pull, (if_empty ? 2u : 0u) | (block ? 1u : 0u), 0);
 }
 
-inline static uint pio_encode_mov(enum pio_src_dest dest, enum pio_src_dest src) {
+/*! \brief Encode a MOV instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `MOV <dest>, <src>`
+ *
+ * \param dest The destination to write data to
+ * \param src The source to take data from
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_mov(enum pio_src_dest dest, enum pio_src_dest src) {
     valid_params_if(PIO_INSTRUCTIONS, !(dest & _PIO_INVALID_MOV_DEST));
     valid_params_if(PIO_INSTRUCTIONS, !(src & _PIO_INVALID_MOV_SRC));
     return _pio_encode_instr_and_src_dest(pio_instr_bits_mov, dest, src & 7u);
 }
 
-inline static uint pio_encode_mov_not(enum pio_src_dest dest, enum pio_src_dest src) {
+/*! \brief Encode a MOV instruction with bit invert
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `MOV <dest>, ~<src>`
+ *
+ * \param dest The destination to write inverted data to
+ * \param src The source to take data from
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_mov_not(enum pio_src_dest dest, enum pio_src_dest src) {
     valid_params_if(PIO_INSTRUCTIONS, !(dest & _PIO_INVALID_MOV_DEST));
     valid_params_if(PIO_INSTRUCTIONS, !(src & _PIO_INVALID_MOV_SRC));
     return _pio_encode_instr_and_src_dest(pio_instr_bits_mov, dest, (1u << 3u) | (src & 7u));
 }
 
-inline static uint pio_encode_mov_reverse(enum pio_src_dest dest, enum pio_src_dest src) {
+/*! \brief Encode a MOV instruction with bit reverse
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `MOV <dest>, ::<src>`
+ *
+ * \param dest The destination to write bit reversed data to
+ * \param src The source to take data from
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_mov_reverse(enum pio_src_dest dest, enum pio_src_dest src) {
     valid_params_if(PIO_INSTRUCTIONS, !(dest & _PIO_INVALID_MOV_DEST));
     valid_params_if(PIO_INSTRUCTIONS, !(src & _PIO_INVALID_MOV_SRC));
     return _pio_encode_instr_and_src_dest(pio_instr_bits_mov, dest, (2u << 3u) | (src & 7u));
 }
 
-inline static uint pio_encode_irq_set(bool relative, uint irq) {
+/*! \brief Encode a IRQ SET instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `IRQ SET <irq> <relative>`
+ *
+ * \param relative true for a `IRQ SET <irq> REL`, false for regular `IRQ SET <irq>`
+ * \param irq the irq number 0-7
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_irq_set(bool relative, uint irq) {
     return _pio_encode_instr_and_args(pio_instr_bits_irq, 0, _pio_encode_irq(relative, irq));
 }
 
-inline static uint pio_encode_irq_clear(bool relative, uint irq) {
+/*! \brief Encode a IRQ WAIT instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `IRQ WAIT <irq> <relative>`
+ *
+ * \param relative true for a `IRQ WAIT <irq> REL`, false for regular `IRQ WAIT <irq>`
+ * \param irq the irq number 0-7
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_irq_wait(bool relative, uint irq) {
+    return _pio_encode_instr_and_args(pio_instr_bits_irq, 1, _pio_encode_irq(relative, irq));
+}
+
+/*! \brief Encode a IRQ CLEAR instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `IRQ CLEAR <irq> <relative>`
+ *
+ * \param relative true for a `IRQ CLEAR <irq> REL`, false for regular `IRQ CLEAR <irq>`
+ * \param irq the irq number 0-7
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_irq_clear(bool relative, uint irq) {
     return _pio_encode_instr_and_args(pio_instr_bits_irq, 2, _pio_encode_irq(relative, irq));
 }
 
-inline static uint pio_encode_set(enum pio_src_dest dest, uint value) {
+/*! \brief Encode a SET instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `SET <dest>, <value>`
+ *
+ * \param dest The destination to apply the value to
+ * \param value The value 0-31
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_set(enum pio_src_dest dest, uint value) {
     valid_params_if(PIO_INSTRUCTIONS, !(dest & _PIO_INVALID_SET_DEST));
     return _pio_encode_instr_and_src_dest(pio_instr_bits_set, dest, value);
 }
 
-inline static uint pio_encode_nop(void) {
+/*! \brief Encode a NOP instruction
+ *  \ingroup pio_instructions
+ *
+ * This is the equivalent of `NOP` which is itself encoded as `MOV y, y`
+ *
+ * \return The instruction encoding with 0 delay and no side set value
+ * \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
+ */
+static inline uint pio_encode_nop(void) {
     return pio_encode_mov(pio_y, pio_y);
 }
 
diff --git a/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h b/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h
index db63142..2aeb647 100644
--- a/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h
+++ b/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h
@@ -54,12 +54,12 @@
 #define PICO_STDIO_USB_RESET_MAGIC_BAUD_RATE 1200
 #endif
 
-// PICO_CONFIG: PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS, Maximum number of milliseconds to wait during initialization for a CDC connection from the host (negative means indefinite) before returning, default=0, group=pico_stdio_usb
+// PICO_CONFIG: PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS, Maximum number of milliseconds to wait during initialization for a CDC connection from the host (negative means indefinite) during initialization, default=0, group=pico_stdio_usb
 #ifndef PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS
 #define PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS 0
 #endif
 
-// PICO_CONFIG: PICO_STDIO_USB_POST_CONNECT_WAIT_DELAY_MS, Number of milliseconds to wait during initialization after a host CDC connection is detected before returning (some host terminals seem to sometimes lose transmissions sent right after connection), default=50, group=pico_stdio_usb
+// PICO_CONFIG: PICO_STDIO_USB_POST_CONNECT_WAIT_DELAY_MS, Number of extra milliseconds to wait when using PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS after a host CDC connection is detected (some host terminals seem to sometimes lose transmissions sent right after connection), default=50, group=pico_stdio_usb
 #ifndef PICO_STDIO_USB_POST_CONNECT_WAIT_DELAY_MS
 #define PICO_STDIO_USB_POST_CONNECT_WAIT_DELAY_MS 50
 #endif