Seeeduino – Sasapea's Lab

Seeeduino XIAO (ATSAMD21) の限界を試すべく、下記投稿のライブラリをポーティングし送信速度がどこまで出せるか試してみた。

Hi-Speed Serial TX Library for AVR Series

ちなみに、Seeeduino XIAO (ATSAMD21) のSERCOM-USARTでは送受信とも最大3Mbpsである。

ライブラリの最高速度は12Mbps~~16Mbps~~だが、さすがに、16MbpsだとGPIOが追い付かなくて無理っぽい感じ．．．8Mbpsならなんとか行けそうな気もするが、Output Driver Strength = 1 は必須かも。

【16Mbps (Output Driver Strength = 0)】

【16Mbps (Output Driver Strength = 1)】

【8Mbps (Output Driver Strength = 0)】

【8Mbps (Output Driver Strength = 1)】

【4Mbps (Output Driver Strength = 0)】

【4Mbps (Output Driver Strength = 1)】

【サンプル・スケッチ】

#include "HSTSerial.h"

#define TX_PORT (32 * 1 + 8) // PB08_A6_D6_TX
#define HSTX HSTSerial<921600, TX_PORT>

uint8_t data[] = {'@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I'};

void setup()
{
  HSTX::begin();
}

void loop()
{
  HSTX::write(data, sizeof(data));
  delay(100);
}

#include "HSTSerial.h"

#define TX_PORT (32 * 1 + 8) // PB08_A6_D6_TX

#define HSTX HSTSerial<921600, TX_PORT>

uint8_t data[] = {'@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I'};

void setup()

{

HSTX::begin();

}

void loop()

{

HSTX::write(data, sizeof(data));

delay(100);

}

【修正履歴】
2020-04-25
オシロで詳しく調べてみたらSingle-Cycle I/O の実行クロック数がヘンだ。連続でHIGH/LOWを繰り返すと確かに１サイクルなのだが、繰り返さない場合は＋１サイクル余計にかかってしまう。つまり、普通に使う限り２サイクルかかるということだ。AHB-APB BridgeのWait stateが入るのかな．．．もしかしてだけど。ということで、ビット当たり３から４クロックへ変更しそれに合わせて通信速度定義を修正。delay cycle数も確認してみたが問題なさそう。でも、まだ計算通りのクロックにならないのはなぜだろう？詳しく観察してみると数サイクル毎に±１サイクル微調整されてるもよう。そもそも armというのは複雑なパイプラインを駆使するＰＣ向けアーキテクチャーのものなので、それをダウングレードして組み込み用にも使えるよって歌い文句にしただけの製品だから命令の実行サイクル数など計算しても意味がないよということらしい．．．知らなかった。orz

2020-04-24
1Mbps超えでエラーになるのはクロックのズレが原因だった。オシロで見るかぎり命令の実行サイクル数がドキュメント通りでなく計算値とかなりかけ離れているようだ。だが、なぜかはわからないがどうやっても調整することができない。仕方ないのでよく使う通信速度をオシロで時間合わせした速度定義を追加しておいた。通信速度を直接指定せずHSTSerial_115200からHSTSerial_12Mまでの通信速度定義を利用するとうまくいくはずだ。
計算上では16Mbpsのはずが最高でも12Mbpsまでしか出なかったがFT232Hを受信相手に最大12Mbpsで送信できることを確認した。但し、12Mbpsでは連続送信で時々データ化けが発生。8Mbps程度が限界かも．．．

2020-04-23
1Mbpsを超える速度では受信エラーになることが発覚。ATtiny85でも8Mbpsで送信できたのに．．．相性の問題か、或いは、送信タイミングが微妙にズレてるのかも。調査が必要だ。

【ライブラリ】
ライブラリは、Cortex-M0+の命令実行サイクルとSingle-Cycle I/O Portに依存してるためCortex-M0を含む他のデバイスでは動作しないことに注意しよう。このライブラリはビットあたり３サイクルかかっているが、AVRのビット・テスト・スキップ命令、或いは、shiftとandの合成命令があれば２サイクルで実行できる。特にAND/OR/XORなどの論理演算と他の命令の組み合わせは頻繁に使われてるはずなのであったらいいなって感じの命令だ。CPUアーキテクチャー云々よりも使いやすいのが一番だと思うが。

ちなみに、Single-Cycle I/O PortのサポートがないCortex-M0に対応したところで限界値はかなり低いと思われるため対応する価値はないかな。たぶん．．．

/*
  HSTSerial.h - Hi Speed TX Serial Library for ATSAMD21

  Baudrate: 48MHz: 115200 -12M bps

  Exsample:

    #include "HSTSerial.h"

    #define TX_PORT (32 * 1 + 8) // PB08_A6_D6_TX
    #define HSTX HSTSerial<921600, TX_PORT>
    
    void setup(void)
    {
      HSTX::begin();
    }

    void loop(void)
    {
      HSTX::write(0x41);
    }

  Copyright (c) 2020 Sasapea's Lab. All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA
*/
#ifndef __HSTSERIAL_H
#define __HSTSERIAL_H

#include "IOBUS.h"

#define HSTSerial_115200   115500
#define HSTSerial_230400   232000
#define HSTSerial_320400   324000
#define HSTSerial_460800   466350
#define HSTSerial_921600   941500
#define HSTSerial_1M      1021000
#define HSTSerial_2M      2090000
#define HSTSerial_3M      3200000
#define HSTSerial_4M      4370000
#define HSTSerial_5M      5550000
#define HSTSerial_6M      6500000
#define HSTSerial_8M      8200000
#define HSTSerial_10M    10000000
#define HSTSerial_12M    11300000

#define HSTSerial_POS(pin)    (pin & 31)
#define HSTSerial_PORT(pin)   (int)(&PORT_IOBUS->Group[pin >> 5])
#define HSTSerial_OUTCLR(pin) (int)(&((PortGroup *)0)->OUTCLR)
#define HSTSerial_OUTSET(pin) (int)(&((PortGroup *)0)->OUTSET)
#define HSTSerial_OUTTGL(pin) (int)(&((PortGroup *)0)->OUTTGL)

#define HSTSerial_DELAY_CYCLE 3  // cycle of delay loop
#define HSTSerial_TXBIT_CYCLE 4  // 3 + (1)???

#define HSTSerial_BIT_CYCLE ((float)F_CPU / BAUDRATE)
#define HSTSerial_CPU_CYCLE (int)(HSTSerial_BIT_CYCLE + 0.5)
#define HSTSerial_DELAY(n) \
  do \
  { \
    int   cycle = 0; \
    float error = HSTSerial_BIT_CYCLE - HSTSerial_CPU_CYCLE; \
    float round = (error < 0 ? -0.5 : 0.5); \
    error -= (int)error; \
    if (((int)(error * (n) + round) ^ (int)(error * ((n) + 1) + round)) & 1) \
      cycle += (error < 0 ? -1 : 1); \
    if ((cycle += HSTSerial_CPU_CYCLE - HSTSerial_TXBIT_CYCLE) > 0) \
    { \
      if (cycle / HSTSerial_DELAY_CYCLE) \
        __asm__ volatile \
        ( \
          "mov r3, %[_COUNT_]" "\n\t" \
          "1: sub r3, #1"      "\n\t" \
          "bne 1b"             "\n\t" \
          : \
          : [_COUNT_] "I" (cycle / HSTSerial_DELAY_CYCLE) \
          : "r3" \
        ); \
      if ((cycle % HSTSerial_DELAY_CYCLE) > 0) \
        __asm__ volatile ("nop"); \
      if ((cycle % HSTSerial_DELAY_CYCLE) > 1) \
        __asm__ volatile ("nop"); \
    } \
  } \
  while (0)

template<uint32_t BAUDRATE, uint32_t PIN>
class HSTSerial
{
  private:

  public:

    static void begin(bool drvstr = true)
    {
      IOBUS::pinMode(PIN, OUTPUT, drvstr);
    }

    static void write(uint8_t data)
    {
      if (HSTSerial_CPU_CYCLE < 256 * HSTSerial_DELAY_CYCLE + HSTSerial_TXBIT_CYCLE - 1)
      {
        __asm__ volatile
        (
          "mov   r0, %[_DATA_]"      "\n\t"
          "add   r1, r0, r0"         "\n\t"
          "eor   r0, r0, r1"         "\n\t"
          "mov   r1, #1"             "\n\t"
          "lsl   r1, r1, %[_POS_]"   "\n\t"
          "mov   r2, %[_PORT_]"      "\n\t"
          "lsl   r2, r2, #24"        "\n\t"
          "mov   r3, %[_PGRP_]"      "\n\t"
          "lsl   r3, r3, #7"         "\n\t"
          "add   r2, r2, r3"         "\n\t"
          "CPSID i"                  "\n\t"
          "str   r1, [r2, %[_REG_]]" "\n\t"
          :
          : [_POS_ ] "I" (PIN & 31)
          , [_REG_ ] "I" (HSTSerial_OUTCLR(PIN))
          , [_PORT_] "I" (HSTSerial_PORT(PIN) >> 24)
          , [_PGRP_] "I" ((HSTSerial_PORT(PIN) >> 7) & 0xFF)
          , [_DATA_] "r" (data)
          : "r1", "r2", "r3"
        );
        HSTSerial_DELAY(0);
        __asm__ volatile
        (
          "lsl   r3, r0, %[_POS_]"   "\n\t"
          "and   r3, r3, r1"         "\n\t"
          "str   r3, [r2, %[_REG_]]" "\n\t"
          :
          : [_POS_ ] "I" (PIN & 31)
          , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
          : "r3"
        );
        HSTSerial_DELAY(1);
        if ((PIN & 31) >= 1)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 1)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (1 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(2);
        if ((PIN & 31) >= 2)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 2)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (2 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(3);
        if ((PIN & 31) >= 3)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 3)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (3 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(4);
        if ((PIN & 31) >= 4)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 4)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (4 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(5);
        if ((PIN & 31) >= 5)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 5)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (5 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(6);
        if ((PIN & 31) >= 6)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 6)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (6 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(7);
        if ((PIN & 31) >= 7)
        {
          __asm__ volatile
          (
            "lsl   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" ((PIN & 31) - 7)
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        else
        {
          __asm__ volatile
          (
            "lsr   r3, r0, %[_POS_]"   "\n\t"
            "and   r3, r3, r1"         "\n\t"
            "str   r3, [r2, %[_REG_]]" "\n\t"
            :
            : [_POS_ ] "I" (7 - (PIN & 31))
            , [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))
            : "r3"
          );
        }
        HSTSerial_DELAY(8);
        __asm__ volatile
        (
          "nop"                      "\n\t"
          "nop"                      "\n\t"
          "str   r1, [r2, %[_REG_]]" "\n\t"
          "CPSIE i"                  "\n\t"
          :
          : [_REG_ ] "I" (HSTSerial_OUTSET(PIN))
        );
        HSTSerial_DELAY(9);
      }
    }

    static void write(uint8_t *buf, uint32_t len)
    {
      while (len--)
        write(*buf++);
    }
};

#endif

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HSTSerial.h - Hi Speed TX Serial Library for ATSAMD21

Baudrate: 48MHz: 115200 -12M bps

Exsample:

#include "HSTSerial.h"

#define TX_PORT (32 * 1 + 8) // PB08_A6_D6_TX

#define HSTX HSTSerial<921600, TX_PORT>

void setup(void)

{

HSTX::begin();

}

void loop(void)

{

HSTX::write(0x41);

}

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Lesser General Public

License as published by the Free Software Foundation; either

version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General

Public License along with this library; if not, write to the

Free Software Foundation, Inc., 59 Temple Place, Suite 330,

Boston, MA 02111-1307 USA

#ifndef __HSTSERIAL_H

#define __HSTSERIAL_H

#include "IOBUS.h"

#define HSTSerial_115200 115500

#define HSTSerial_230400 232000

#define HSTSerial_320400 324000

#define HSTSerial_460800 466350

#define HSTSerial_921600 941500

#define HSTSerial_1M 1021000

#define HSTSerial_2M 2090000

#define HSTSerial_3M 3200000

#define HSTSerial_4M 4370000

#define HSTSerial_5M 5550000

#define HSTSerial_6M 6500000

#define HSTSerial_8M 8200000

#define HSTSerial_10M 10000000

#define HSTSerial_12M 11300000

#define HSTSerial_POS(pin) (pin & 31)

#define HSTSerial_PORT(pin) (int)(&PORT_IOBUS->Group[pin >> 5])

#define HSTSerial_OUTCLR(pin) (int)(&((PortGroup *)0)->OUTCLR)

#define HSTSerial_OUTSET(pin) (int)(&((PortGroup *)0)->OUTSET)

#define HSTSerial_OUTTGL(pin) (int)(&((PortGroup *)0)->OUTTGL)

#define HSTSerial_DELAY_CYCLE 3 // cycle of delay loop

#define HSTSerial_TXBIT_CYCLE 4 // 3 + (1)???

#define HSTSerial_BIT_CYCLE ((float)F_CPU / BAUDRATE)

#define HSTSerial_CPU_CYCLE (int)(HSTSerial_BIT_CYCLE + 0.5)

#define HSTSerial_DELAY(n) \

do \

{ \

int cycle = 0; \

float error = HSTSerial_BIT_CYCLE - HSTSerial_CPU_CYCLE; \

float round = (error < 0 ? -0.5 : 0.5); \

error -= (int)error; \

if (((int)(error * (n) + round) ^ (int)(error * ((n) + 1) + round)) & 1) \

cycle += (error < 0 ? -1 : 1); \

if ((cycle += HSTSerial_CPU_CYCLE - HSTSerial_TXBIT_CYCLE) > 0) \

{ \

if (cycle / HSTSerial_DELAY_CYCLE) \

__asm__ volatile \

( \

"mov r3, %[_COUNT_]" "\n\t" \

"1: sub r3, #1" "\n\t" \

"bne 1b" "\n\t" \

: \

: [_COUNT_] "I" (cycle / HSTSerial_DELAY_CYCLE) \

: "r3" \

); \

if ((cycle % HSTSerial_DELAY_CYCLE) > 0) \

__asm__ volatile ("nop"); \

if ((cycle % HSTSerial_DELAY_CYCLE) > 1) \

__asm__ volatile ("nop"); \

} \

while (0)

template<uint32_t BAUDRATE, uint32_t PIN>

class HSTSerial

{

private:

public:

static void begin(bool drvstr = true)

{

IOBUS::pinMode(PIN, OUTPUT, drvstr);

}

static void write(uint8_t data)

{

if (HSTSerial_CPU_CYCLE < 256 * HSTSerial_DELAY_CYCLE + HSTSerial_TXBIT_CYCLE - 1)

{

__asm__ volatile

(

"mov r0, %[_DATA_]" "\n\t"

"add r1, r0, r0" "\n\t"

"eor r0, r0, r1" "\n\t"

"mov r1, #1" "\n\t"

"lsl r1, r1, %[_POS_]" "\n\t"

"mov r2, %[_PORT_]" "\n\t"

"lsl r2, r2, #24" "\n\t"

"mov r3, %[_PGRP_]" "\n\t"

"lsl r3, r3, #7" "\n\t"

"add r2, r2, r3" "\n\t"

"CPSID i" "\n\t"

"str r1, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (PIN & 31)

, [_REG_ ] "I" (HSTSerial_OUTCLR(PIN))

, [_PORT_] "I" (HSTSerial_PORT(PIN) >> 24)

, [_PGRP_] "I" ((HSTSerial_PORT(PIN) >> 7) & 0xFF)

, [_DATA_] "r" (data)

: "r1", "r2", "r3"

);

HSTSerial_DELAY(0);

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (PIN & 31)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

HSTSerial_DELAY(1);

if ((PIN & 31) >= 1)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 1)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (1 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(2);

if ((PIN & 31) >= 2)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 2)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (2 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(3);

if ((PIN & 31) >= 3)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 3)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (3 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(4);

if ((PIN & 31) >= 4)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 4)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (4 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(5);

if ((PIN & 31) >= 5)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 5)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (5 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(6);

if ((PIN & 31) >= 6)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 6)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (6 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(7);

if ((PIN & 31) >= 7)

{

__asm__ volatile

(

"lsl r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" ((PIN & 31) - 7)

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

else

{

__asm__ volatile

(

"lsr r3, r0, %[_POS_]" "\n\t"

"and r3, r3, r1" "\n\t"

"str r3, [r2, %[_REG_]]" "\n\t"

: [_POS_ ] "I" (7 - (PIN & 31))

, [_REG_ ] "I" (HSTSerial_OUTTGL(PIN))

: "r3"

);

}

HSTSerial_DELAY(8);

__asm__ volatile

(

"nop" "\n\t"

"str r1, [r2, %[_REG_]]" "\n\t"

"CPSIE i" "\n\t"

: [_REG_ ] "I" (HSTSerial_OUTSET(PIN))

);

HSTSerial_DELAY(9);

}

static void write(uint8_t *buf, uint32_t len)

{

while (len--)

write(*buf++);

}

};

#endif

【参照ライブラリ】
Seeeduino XIAO (ATSAMD21G18) のGPIO速度

タグ: Seeeduino

Hi-Speed Serial TX Library for Seeeduino XIAO (ATSAMD21)