| Both sides previous revision Previous revision Next revision | Previous revision |
| docs:techref:hardware:port.jtag.utilization [2018/03/31 23:22] – ↷ Page moved from docs:hardware:port.jtag.utilization to docs:techref:hardware:port.jtag.utilization bobafetthotmail | docs:techref:hardware:port.jtag.utilization [2019/09/02 14:01] (current) – non-existing link targets removed tmomas |
|---|
| ====== JTAG utilization ====== | ====== JTAG utilization ====== |
| 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]] or [[docs:hardware:port.jtag.cables#buffered]] + redirect from something.wiggler to this article | * -> [[docs:techref:hardware:port.jtag.cable.buffered]] |
| * -> [[docs:hardware:port.jtag.cable.unbuffered]] or [[docs:hardware:port.jtag.cables#unbuffered]] | * -> [[docs:techref:hardware:port.jtag.cable.unbuffered]] |
| * -> [[docs:hardware:port.jtag.utilization]]/instruction/usage (in addition to the YouTube Videos ;-) | * -> [[docs:techref:hardware:port.jtag.utilization]]/instruction/usage (in addition to the YouTube Videos ;-) |
| * -> [[docs:guide-user:troubleshooting:generic.debrick]] there is content on utilizing JTAG (link to it or from it, don't leave double content!) | * -> [[docs:guide-user:troubleshooting:generic.debrick]] there is content on utilizing JTAG (link to it or from it, don't leave double content!) |
| * -> [[/toh/davolink/dv-201amr#jtag]] there is content on utilizing JTAG (link to it or from it, don't leave double content! unless specific) | * -> [[/toh/davolink/dv-201amr#jtag]] there is content on utilizing JTAG (link to it or from it, don't leave double content! unless specific) |
| * -> [[/toh/davolink/dv-201amr#jtag]] there is content on utilizing JTAG (link to it or from it, don't leave double content! unless specific) | * -> [[/toh/davolink/dv-201amr#jtag]] there is content on utilizing JTAG (link to it or from it, don't leave double content! unless specific) |
| |
| Inside the zip file download for the [[http://downloads.openwrt.org/utils/HairyDairyMaid_WRT54G_Debrick_Utility_v48.zip|Hairydairymaid WRT54G Debrick Utility v48]] there is a PDF file that describes the software and how to use it. He specifically talks about using an unbuffered cable and pointedly notes that the cable he uses does **not** tie pin 1 of the JTAG header to anything. | Inside the zip file download for the //Hairydairymaid WRT54G Debrick Utility v48// there is a PDF file that describes the software and how to use it. He specifically talks about using an unbuffered cable and pointedly notes that the cable he uses does **not** tie pin 1 of the JTAG header to anything. |
| |
| That's all well and good for an unbuffered cable, but if you //do// happen to have a buffered Wiggler-style cable then you //will// have to deal with the nTRST signal. The Hairydairymaid software doesn't account for that signal line since the recommended cable doesn't carry it, but your Wiggler-style cable //does// use that signal and the debrick utility will //not// work out-of-the-box with a Wiggler-style cable as a result. The reason for this is because the software leaves the output for the nTRST line at logic-level 0, which means the signal coming out of your cable to the JTAG header will always be asserted, and as a result the JTAG circuitry inside your router will forever be resetting itself. | That's all well and good for an unbuffered cable, but if you //do// happen to have a buffered Wiggler-style cable then you //will// have to deal with the nTRST signal. The Hairydairymaid software doesn't account for that signal line since the recommended cable doesn't carry it, but your Wiggler-style cable //does// use that signal and the debrick utility will //not// work out-of-the-box with a Wiggler-style cable as a result. The reason for this is because the software leaves the output for the nTRST line at logic-level 0, which means the signal coming out of your cable to the JTAG header will always be asserted, and as a result the JTAG circuitry inside your router will forever be resetting itself. |