Disabling JTAG

Question

We use RH850/FL1 for an automotive product. To enhance security, we will need to disable/password-protect JTAG in the market. 
 
 While I am anticipating any registers are available to do that, I could not find any statements related to that in the RH850-F1L HW User Manual v1.30 . Can you please the refister name and corresponding pages in the manual? 
 
 Thank you so much for your support. 
 Kohei

JimB · Accepted Answer

The JTAG / debug interface is enabled via the option bytes. 
 
 The option bytes can be changed via the serial programming interface, as such if serial programming is not protected, the debug interface can be enabled and a debugger attached. 
 The security ID applies to both the debug interface and the serial programming interface. Most customers set this value, which allows a field return to be analyzed. If the interfaces are completely disabled, there is no way to investigate problems. 
 The overall security of the device should be considered.

Backle Down To · Answer

Thank you so much for your kind reply. 
 I now understand that when 0 is set to OPJTAG, JTAG is disabled. As you pointed out, killing JTAG completely is not a good strategy for our product, as analyzing return parts is indispensable. 
 I am planning to adopt t he security ID instead. Terribly sorry but is this feature enabled by register configurations again? I would appreiciate if you would share places that expound on the security ID in the manual. 
 Thank you so much, 
 Kohei (Tokyo)

Disabling JTAG

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