====== BSCAN学习 ======

参考IEEE.Std.1149.6-2003.pdf
===== - JTAG TAP FSM =====
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===== - tessent bscan interface =====
左侧是开了ac_control选项，右侧没有开，生成出来bscan interface模块的区别：

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===== - AC test signal =====

^ tessent tap              ^ SNPS PHY信号  ^ 说明                                                                                    ^
| to_bscan_ac_mode_en      | bs_acmode     | 表示EXTEST_PULSE or EXTEST_TRAIN有效，处于BSCAN AC测试模式                              |
| to_bscan_ac_signal       | bs_actest     | 在JTAG IDLE状态，测试信号拉高（EXTEST_PULSE模式）,测试信号按TCK周期翻转（EXTEST_TRAIN)  |
| to_bscan_ac_init_clock0  | bs_rx_init    |                                                                                         |
| to_bscan_ac_init_clock1  |               | ~to_bscan_ac_init_clock0                                                                |

initclk\\
{{:edastudy:bscan:pasted:20250524-210226.png?nolink}}

{{:edastudy:bscan:pasted:20250523-150523.png?nolink}}

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ac test signal, 只在RTI模式下数据才有效， pulse or train\\
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<code>
ACMODE = EXTEST_TRAIN | EXTEST_PULSE;

ac_signal = RTI & ACMODE;

bscan_select = EXTEST_decoded | INTEST_decoded | EXTEST_PULSE_decoded |
               EXTEST_TRAIN_decoded | EXTEST_PRELOAD_decoded;

ac_init_clk0 = ac_init_clk_EXTEST | ac_init_clk_EXTEST_TRAIN_OR_PULSE;
ac_init_clk1 = ~ ac_init_clk0;


ac_init_clk_EXTEST = SDR & bscan_select;
ac_init_clk_EXTEST_TRAIN_OR_PULSE = (E1DR | E2DR) & ACMODE;
</code>


===== - Input test receivers =====
接收器在接收的时候分为DC Coupled和AC Coupled。

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**EXTEST测试时，在capture-DR状态，TCK下降沿，接收器给一个初始值**

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**AC EXTEST测试时，在TCK上升沿，updata DR状态时前，接收器给一个初始值**

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接收器示范电路如下：


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===== - Output drivers =====

output driver不会太特殊

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===== - instruction =====
==== - EXTEST_PULSE ====
{{:edastudy:pasted:20231227-145507.png?nolink}}


==== - EXTEST_TRAIN ====
{{:edastudy:pasted:20231227-145540.png?nolink}}

===== - clockdr & updatedr =====

<code verilog>
clockir = ((pstate == capture_IR) || (pstate == shift_IR)) ? tck : 1'b1;
clockdr = ((pstate == capture_DR) || (pstate == shift_DR)) ? tck : 1'b1;
</code>
在capture状态capture数据，在shift状态，shift数据。

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===== - tessent BC cell =====
ref: bsda_ref.pdf
==== - BC_1 ====
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==== - BC_2 ====
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==== - BC_2_A ====
{{:edastudy:pasted:20240122-094212.png?nolink}}

==== - BC_2_A_EXT ====
{{:edastudy:pasted:20240122-094535.png?nolink}}

==== - BC_2_B ====
{{:edastudy:pasted:20240122-094324.png?nolink}}


==== - BC_3 ====
{{:edastudy:pasted:20240122-094405.png?nolink}}


==== - BC_4 ====
{{:edastudy:pasted:20240122-094446.png?nolink}}


==== - BC_5 ====
{{:edastudy:pasted:20240122-094759.png?nolink}}

==== - BC_7 ====
{{:edastudy:pasted:20240122-094836.png?nolink}}


==== - BC_7_LOW ====
{{:edastudy:pasted:20240122-094917.png?nolink}}

==== - BC_8 ====
{{:edastudy:pasted:20240122-094959.png?nolink}}

==== - BC_9 ====
{{:edastudy:pasted:20240122-095034.png?nolink}}

==== - BC_10 ====
{{:edastudy:pasted:20240122-095104.png?nolink}}

===== - tessent AC cell =====
ref: bsda_ref.pdf

==== - AC_1 ====
{{:edastudy:pasted:20240122-095245.png?nolink}}

==== - AC_2 ====
{{:edastudy:pasted:20240122-095308.png?nolink}}

==== - AC_7 ====
{{:edastudy:pasted:20240122-095342.png?nolink}}

==== - AC_7_LOW ====
{{:edastudy:pasted:20240122-095406.png?nolink}}


==== - AC_8 ====
{{:edastudy:pasted:20240122-095446.png?nolink}}


==== - AC_9 ====
{{:edastudy:pasted:20240122-095515.png?nolink}}


==== - AC_10 ====
{{:edastudy:pasted:20240122-095540.png?nolink}}


===== - IEEE 1149.1 BSCAN BC cell =====

  * BC_1, input cell, control cell, capture misson input
  * BC_2, input cell, control cell, capture misson output
  * BC_4, Observe-only input cell without control
  * BC_7, BIDI双向 data cell; capture UPD/PAD input/misson output
  * BC_8, BIDI双向 data cell; capture PAD output
  * BC_9, self-monitor output cell; mode 4 capture PAD output, else capture mission input
  * BC_10, self-monitor output cell; capture PAD output only


==== - BC_1 ====
**mode**

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==== - BC_2 ====
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{{:edastudy:pasted:20240119-161454.png?nolink}}

==== - BC_3 ====
<color #ed1c24>个人觉得BC_3不会使用</color>

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==== - BC_4 ====
{{:edastudy:pasted:20240119-161555.png?nolink}}

==== - BC_5 ====

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==== - BC_7 ====
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{{:edastudy:pasted:20240119-161818.png?nolink}}


==== - BC_8 ====
**mode**

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{{:edastudy:pasted:20240119-161856.png?nolink}}

**bc_2 control + bc_8**

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==== - BC_9 ====
{{:edastudy:pasted:20240119-164214.png?nolink}}

{{:edastudy:pasted:20240119-161929.png?nolink}}


==== - BC_10 ====
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===== - BSCAN AC cell =====

  * AC_SelX, 控制选择AC/DC测试模式， capture的值永远是X，即不关注capture到的值
  * AC_SelU, 控制选择AC/DC测试模式， capture的值是UPD，即capture到的值是上一次配置的AC/DC的选择值。
  * AC_1, input cell, control cell, capture misson input
  * AC_2, input cell, control cell, capture misson output
  * AC_7, BIDI双向 data cell; capture UPD/PAD input/misson output
  * AC_8, BIDI双向 data cell; capture PAD output
  * AC_9, self-monitor output cell; mode 4 capture PAD output, else capture mission input
  * AC_10, self-monitor output cell; capture PAD output only


^                                                               ^ mode 1  ^ mode 2  ^ mode 3  ^ mode 4  ^ mode 5  ^
| EXTEST                                                        | 1       | 0       | 1       | 1       | 1       |
| PRELOAD                                                       | 0       | 0       | 1       | X       | 0       |
| SAMPLE                                                        | 0       | 0       | 1       | 0       | 0       |
| INTEST                                                        | 0       | 1       | 0       | 0       | 1       |
| RUNBIST                                                       | X       | X       | 0       | X       | 1       |
| CLAMP                                                         | 1       | X       | 1       | X       | 1       |
| HIGHZ                                                         | X       | X       | 0       | X       | X       |
| NOTES:\\ 1. EXTEST inluce EXTEST, EXTEST_PLUSE, EXTEST_TRAIN                                               ||||||


==== - AC_SelX ====
{{:edastudy:pasted:20231227-144008.png?nolink}}

==== - AC_SelU ====
{{:edastudy:pasted:20231227-144100.png?nolink}}
==== - AC_1 ====
{{:edastudy:pasted:20231227-144150.png?nolink}}

==== - AC_2 ====
{{:edastudy:pasted:20231227-144237.png?nolink}}

==== - AC_7 ====
{{:edastudy:pasted:20231227-144322.png?nolink}}

==== - AC_8 ====
{{:edastudy:pasted:20231227-144400.png?nolink}}

==== - AC_9 ====
{{:edastudy:pasted:20231227-144439.png?nolink}}

==== - AC_10 ====

{{:edastudy:pasted:20231227-144505.png?nolink}}

===== - BSCAN指令 =====

==== - SAMPLE ====
只sample采样 capture pin input & output值，而不能影响其input pin到内部逻辑值和output pin到PAD的状态。

==== - PRELOAD ====
主要用来更新update DR的值，这个值在后面的测试指令作用下，将会直接被驱动到output PAD脚；如果值没有初始化，将不确定输出的是什么值。

一般后面会再跟一个EXTEST指令，将PRELOAD初始化的值驱动到output PAD上。