树莓派4B 使用gpio readall无法查询到管脚信息的问题及解决办法

树莓派4B 安装的系统版本是2019-06-20-raspbian-buster-full.img
1.安装网上的步骤（https://blog.youkuaiyun.com/m0_37509650/article/details/85403217）修改了串口映射，想测试串口通信功能，但发现使用gpio readall命令时，出现无法查询到管脚信息的错误：

pi@raspberrypi:~ $ gpio readall
Oops - unable to determine board type... model: 17
pi@raspberrypi:~ $ gpio -v
gpio version: 2.50
Copyright (c) 2012-2018 Gordon Henderson
This is free software with ABSOLUTELY NO WARRANTY.
For details type: gpio -warranty

Raspberry Pi Details:
  Type: Unknown17, Revision: 01, Memory: 0MB, Maker: Sony 
  * Device tree is enabled.
  *--> Raspberry Pi 4 Model B Rev 1.1
  * This Raspberry Pi supports user-level GPIO access.

经过查找资料，终于在这个网站http://wiringpi.com/wiringpi-updated-to-2-52-for-the-raspberry-pi-4b/上找到了解决办法。

在树莓派的终端输入以下命令：

cd /tmp
wget https://project-downloads.drogon.net/wiringpi-latest.deb
sudo dpkg -i wiringpi-latest.deb

等待下载完毕,

pi@raspberrypi:~ $ cd /tmp
pi@raspberrypi:/tmp $ wget https://project-downloads.drogom.net/wiringpi-latest.deb
--2019-11-01 16:01:30--  https://project-downloads.drogom.net/wiringpi-latest.deb
正在解析主机 project-downloads.drogom.net (project-downloads.drogom.net)... 失败：未知的名称或服务。
wget: 无法解析主机地址 “project-downloads.drogom.net”
pi@raspberrypi:/tmp $ wget https://project-downloads.drogon.net/wiringpi-latest.deb
--2019-11-01 16:02:06--  https://project-downloads.drogon.net/wiringpi-latest.deb
正在解析主机 project-downloads.drogon.net (project-downloads.drogon.net)... 188.246.205.22, 2a03:9800:10:7b::2
正在连接 project-downloads.drogon.net (project-downloads.drogon.net)|188.246.205.22|:443... 已连接。
已发出 HTTP 请求，正在等待回应... 200 OK
长度：52260 (51K) [application/x-debian-package]
正在保存至: “wiringpi-latest.deb”

wiringpi-latest.deb             100%[=====================================================>]  51.04K  1.12KB/s  用时 45s     

2019-11-01 16:03:03 (1.12 KB/s) - 已保存 “wiringpi-latest.deb” [52260/52260])

执行以下命令安装，

sudo dpkg -i wiringpi-latest.deb

安装完成后，再次查询，成功读取管脚信息，

pi@raspberrypi:/tmp $ gpio readall
 +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
 |   2 |   8 |   SDA.1 |   IN | 1 |  3 || 4  |   |      | 5v      |     |     |
 |   3 |   9 |   SCL.1 |   IN | 1 |  5 || 6  |   |      | 0v      |     |     |
 |   4 |   7 | GPIO. 7 |   IN | 1 |  7 || 8  | 1 | ALT0 | TxD     | 15  | 14  |
 |     |     |      0v |      |   |  9 || 10 | 1 | ALT0 | RxD     | 16  | 15  |
 |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 0 | IN   | GPIO. 1 | 1   | 18  |
 |  27 |   2 | GPIO. 2 |   IN | 0 | 13 || 14 |   |      | 0v      |     |     |
 |  22 |   3 | GPIO. 3 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO. 4 | 4   | 23  |
 |     |     |    3.3v |      |   | 17 || 18 | 0 | IN   | GPIO. 5 | 5   | 24  |
 |  10 |  12 |    MOSI |   IN | 0 | 19 || 20 |   |      | 0v      |     |     |
 |   9 |  13 |    MISO |   IN | 0 | 21 || 22 | 0 | IN   | GPIO. 6 | 6   | 25  |
 |  11 |  14 |    SCLK |   IN | 0 | 23 || 24 | 1 | IN   | CE0     | 10  | 8   |
 |     |     |      0v |      |   | 25 || 26 | 1 | IN   | CE1     | 11  | 7   |
 |   0 |  30 |   SDA.0 |   IN | 1 | 27 || 28 | 1 | IN   | SCL.0   | 31  | 1   |
 |   5 |  21 | GPIO.21 |   IN | 1 | 29 || 30 |   |      | 0v      |     |     |
 |   6 |  22 | GPIO.22 |   IN | 1 | 31 || 32 | 0 | IN   | GPIO.26 | 26  | 12  |
 |  13 |  23 | GPIO.23 |   IN | 0 | 33 || 34 |   |      | 0v      |     |     |
 |  19 |  24 | GPIO.24 |   IN | 0 | 35 || 36 | 0 | IN   | GPIO.27 | 27  | 16  |
 |  26 |  25 | GPIO.25 |   IN | 0 | 37 || 38 | 0 | IN   | GPIO.28 | 28  | 20  |
 |     |     |      0v |      |   | 39 || 40 | 0 | IN   | GPIO.29 | 29  | 21  |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+

综上，树莓派4B中查询不到gpio管脚信息的原因是由于wiringpi版本太旧，与系统不匹配造成的。