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docs:techref:hardware:port.jtag.cables [2018/03/31 23:22] – ↷ Page moved from docs:hardware:port.jtag.cables to docs:techref:hardware:port.jtag.cables bobafetthotmaildocs:techref:hardware:port.jtag.cables [2019/11/09 19:43] (current) – [JTAG Cables] hri33
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 ====== JTAG Cables ====== ====== JTAG Cables ======
-JTAG stands for [[wp>Joint Test Action Group]], which is an [[wp>Institute of Electrical and Electronics Engineers|IEEE]] work group defining an electrical interface for [[docs:hardware:ic|integrated circuit]] **//testing//** and **//programming//**.+JTAG stands for [[wp>Joint Test Action Group]], which is an [[wp>Institute of Electrical and Electronics Engineers|IEEE]] work group defining an electrical interface for [[docs:techref:hardware:ic|integrated circuit]] **//testing//** and **//programming//**.
  
-  * -> [[docs:hardware:port.jtag]] (this article) +  * -> [[docs:techref:hardware:port.jtag]] (this article) 
-    * -> [[docs:hardware:port.jtag.cables]] (homemade cables) +    * -> [[docs:techref:hardware:port.jtag.cables]] (homemade cables) 
-    * -> [[docs:hardware:port.jtag.cable.buffered]] +    * -> [[docs:techref:hardware:port.jtag.cable.buffered]] 
-    * -> [[docs:hardware:port.jtag.cable.unbuffered]] +    * -> [[docs:techref:hardware:port.jtag.cable.unbuffered]] 
-  * -> [[docs:hardware:port.jtag.utilization]]+  * -> [[docs:techref:hardware:port.jtag.utilization]]
     * -> [[docs:guide-user:troubleshooting:generic.debrick]] there is content utilizing the JTAG  (link to it or from it, don't leave double content!)     * -> [[docs:guide-user:troubleshooting:generic.debrick]] there is content utilizing the JTAG  (link to it or from it, don't leave double content!)
     * -> [[/toh/davolink/dv-201amr#jtag]] again milk it for generic content     * -> [[/toh/davolink/dv-201amr#jtag]] again milk it for generic content
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 Driving a JTAG interface through the parallel port on a PC is a slow proposition. //Really// slow. This is due more to the nature of the parallel port connection than an inherent limit of the JTAG specification. In fact, the JTAG spec allows for up to 25 million bits-per-second transfers. With a parallel port cable, however, you will be lucky to achieve more than about 400,000 bits-per-second. With these speeds it is not unusual to spend 25 minutes writing a mere 256 KB of data over a JTAG cable. Programming an entire 2 MB or 4 MB flash chip can literally take hours. It's worth it, however, if you have an otherwise worthless device on your hands and JTAG is the only way to revive it. The Macraigor Raven and USB JTAG adapters are much faster, but there are no known schematic to implement it. Driving a JTAG interface through the parallel port on a PC is a slow proposition. //Really// slow. This is due more to the nature of the parallel port connection than an inherent limit of the JTAG specification. In fact, the JTAG spec allows for up to 25 million bits-per-second transfers. With a parallel port cable, however, you will be lucky to achieve more than about 400,000 bits-per-second. With these speeds it is not unusual to spend 25 minutes writing a mere 256 KB of data over a JTAG cable. Programming an entire 2 MB or 4 MB flash chip can literally take hours. It's worth it, however, if you have an otherwise worthless device on your hands and JTAG is the only way to revive it. The Macraigor Raven and USB JTAG adapters are much faster, but there are no known schematic to implement it.
  
-There are a many variants of the LPT-to-JTAG cables. All of them are different in the LPT pins -to- JTAG pins mapping and may be in the buffered and unbuffered variant.+There are many variants of the LPT-to-JTAG cables. All of them are different in the LPT pins -to- JTAG pins mapping and may be in the buffered and unbuffered variant.
  
  
  
  • Last modified: 2018/03/31 23:22
  • by bobafetthotmail