Differences

This shows you the differences between two versions of the page.

--- gs1900-48 [2022/04/18 12:30] – Move firmware section up svanheule
+++ gs1900-48 [2022/04/18 15:16] – Add JTAG tag svanheule
@@ Line 33: / Line 33: @@
 {{wiki:gs1900-48_board2.jpg?200}}
-=== Hard reset circuit ===
+==== JTAG ====
+The board has an unpopulated eJTAG header. The SMD resistor configuration is such that the interface is disabled by default. To be able to use the JTAG interface, the following changes need to be made:
+  * R171 permanently asserts nTRST. Move R171 (pull-down) to R525 (pull-up) to allow remote assertion of nTRST.
+  * R48 is unpopulated, leaving nSRST unconnected. (optional) Add a 0 ohm resistor to complete the connection.
+  * Add 2×7 pin header, or at least add connections to TDI, TDO, TCK, TMS and (one) GND pins.
+With these modifications, two devices will be found in the JTAG chain:
+<code>
+Info : JTAG tap: auto0.tap tap/device found: 0x00001001 (mfg: 0x000 (<invalid>), part: 0x0001, ver: 0x0)
+Info : JTAG tap: auto1.tap tap/device found: 0x00000001 (mfg: 0x000 (<invalid>), part: 0x0000, ver: 0x0)
+</code>
+==== Hard reset circuit ====
 {{wiki:zyxel:gs1900-48-gpio-reset-crop.jpg?200}} {{wiki:zyxel:gs1900-48-gpio-reset-bodge.jpg?200}}
@@ Line 209: / Line 222: @@
   * [[https://download.zyxel.com/GS1900-48/datasheet/GS1900-48_19.pdf | Product datasheet]]
-{{tag>zyxel-gs1900}}
+{{tag>zyxel-gs1900}} {{tag>jtag}}