Register Transfer Level Design with Verilog (1) [ebook]

設計程式之所以有趣不外乎是它的千變萬化，同樣的結果卻有不同的寫法。

但這些不同寫法當中也並沒有分誰對誰錯，也沒有制定標準來規範何事該用何解。

這也就是我們設計者的珍貴！！

[1] Primitive Instantiations

在Verilog中最基本的邏輯閘便稱為Primitive，使用最基本的primitive為基礎來設計別稱Primitive Instantiations。

[2] Assign Statements

透過Primitive gates在利用assign將結果牽線別有更多變的結果。

[3] Conditional Expression

顧名思義，就是條件式的表示方法！這也是能將硬邦邦的硬體注入多變思想的刀刃。

[4] Procedural Blocks

至於這套程序則是非常高接的處理程序，往往是很多Conditional Expression所組成。

所有教課書不往往儘說這些道理，但這些確有哪些不同呢？其實在我的見解就如下

[1]就是利用最基本的邏輯閘組成所需的系統。

[2]的概念就與數學相似，利用運算元來表示系統。

[3]條件是就有如黑盒子概念，拿數位邏輯的概念來說，就是將系統使用Boolean Expressions來呈現，輸入與輸出的關係就有如條件班達成。

[4]則是透過程序流程來分析結果，當然所耗的資源都不盡相同。

Reference

<1>Verilog Digital System Design - RT Level Synthesis, Testbench and Verification

RF in IOT

      最近開始研究起RF通訊這方面的資訊，目前大家都鎖定在IOT這個區塊，各家大廠都推出屬於自己的協定來因應產品需求，好比Apple Homekit，Google Brillo。但由於各家都有各自條件優勢，所以對於這整塊市場還在群雄爭霸當中。
       基本上經過了解後發現這幾項技術還在開發階段，所以目前相關的文獻跟發展都還沒有到穩定成熟的狀況，也就是代表還有很多可以值得細玩的技術，此外切入門檻相對許多大系統這是比較容易許多，不過，卻可以增加不同產業的產品功能性，就好比醫療產業（透過藍芽或wifi做資料顯示傳送，省去許多空間）。
      技術層面來看硬體不外乎的就是在意耗電流以及RF的電路，至於訊號是屬於FSK, GSK, PSK, QPSK, DQPSK[5]，就不列入細部考慮，畢竟這是一項時間，空間，能量的平衡槓桿，沒有對與錯沒有是與非，在應用的角度上會有各自的優勢，然而軟體就是需要瞭解藍芽的協定或是其他協定(Thread)[4]，但以目前IOT所要結合網際網路的趨勢是在IPV6，主要是在於它相較TCP/IP，IPV4來說有更多的位址可以使用，但目前卻還有存在相對的風險[3]。
       其實在軟體方面有許多很好的切入點及應用是值得深入研究發展。

Reference
[1]http://www.nordicsemi.com/eng/About-us
[2]NordicSemi-eBook-IoT-Opportunity-Risks-Strategy
[3]http://blog.nordicsemi.com/getconnected/is-the-internet-ready-for-iot
[4]http://www.2cm.com.tw/markettrend_content.asp?sn=1512030005
[5]https://en.wikipedia.org/wiki/List_of_2.4_GHz_radio_use

close timer of kernel

 

if (timer_pending(&handshking_timer))
{
    del_timer_sync(&handshking_timer);
    //init_timer(&handshking_timer);
}

create and cloase of kernel thread

Referece

http://stackoverflow.com/questions/5280693/kernel-thread-implementation

tips for control uart

http://www.termsys.demon.co.uk/vtansi.htm

Linux I2C Driver

 

linux-source/Documentation/i2c/ has lot of the information you'd need. .../writing-clients.txt is a good place to start.

Have a look at the online version:

https://www.kernel.org/doc/Documentation/i2c/writing-clients

There is an okay sort of a tutorial at:

http://renjucnair.blogspot.ca/2012/01/writing-i2c-client-driver.html

Here is a good commentary on someone writing an i2c driver and has a tutorial feel to it:

http://www.embedded-bits.co.uk/2009/i2c-in-the-2632-linux-kernel/

Here is some sample code:

http://code.google.com/p/ldd-templates/source/browse/drivers/i2c/sample-i2c-client.c

Reference

http://stackoverflow.com/questions/16728587/i2c-driver-in-linux

Getopt

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int
main (int argc, char **argv)
{
  int aflag = 0;
  int bflag = 0;
  char *cvalue = NULL;
  int index;
  int c;

  opterr = 0;

  while ((c = getopt (argc, argv, "abc:")) != -1)
    switch (c)
      {
      case 'a':
        aflag = 1;
        break;
      case 'b':
        bflag = 1;
        break;
      case 'c':
        cvalue = optarg;
        break;
      case '?':
        if (optopt == 'c')
          fprintf (stderr, "Option -%c requires an argument.\n", optopt);
        else if (isprint (optopt))
          fprintf (stderr, "Unknown option `-%c'.\n", optopt);
        else
          fprintf (stderr,
                   "Unknown option character `\\x%x'.\n",
                   optopt);
        return 1;
      default:
        abort ();
      }

  printf ("aflag = %d, bflag = %d, cvalue = %s\n",
          aflag, bflag, cvalue);

  for (index = optind; index < argc; index++)
    printf ("Non-option argument %s\n", argv[index]);
  return 0;
}

Here are some examples showing what this program prints with different combinations of arguments:

% testopt
aflag = 0, bflag = 0, cvalue = (null)

% testopt -a -b
aflag = 1, bflag = 1, cvalue = (null)

% testopt -ab
aflag = 1, bflag = 1, cvalue = (null)

% testopt -c foo
aflag = 0, bflag = 0, cvalue = foo

% testopt -cfoo
aflag = 0, bflag = 0, cvalue = foo

% testopt arg1
aflag = 0, bflag = 0, cvalue = (null)
Non-option argument arg1

% testopt -a arg1
aflag = 1, bflag = 0, cvalue = (null)
Non-option argument arg1

% testopt -c foo arg1
aflag = 0, bflag = 0, cvalue = foo
Non-option argument arg1

% testopt -a -- -b
aflag = 1, bflag = 0, cvalue = (null)
Non-option argument -b

% testopt -a -
aflag = 1, bflag = 0, cvalue = (null)
Non-option argument -

An option character in this string can be followed by a colon (‘:’) to indicate that it takes a required argument. If an option character is followed by two colons (‘::’), its argument is optional.

This optarg is set by getopt to point at the value of the option argument, for those options that accept arguments.

 

Reference

[1] http://www.gnu.org/software/libc/manual/html_node/Using-Getopt.html

[2] http://www.gnu.org/software/libc/manual/html_node/Example-of-Getopt.html

[3] http://en.wikipedia.org/wiki/Getopt