Processor Expert SoftwareのトピックRe: bogus default values in Init_NFC

bogus default values in Init_NFC

bowerymarc — Sun, 18 May 2014 20:30:49 GMT

The Init_NFC component defaults with some out of range values. Naturally the user of these 'expert' components assumes that the default instantiation, while possibly not optimized, should at least function correctly. Such is not the case here. These parameters discussed below should have their defaults changed to valid values. Further, this and all other PE components should be reviewed by the PE teams to insure there are no other invalid values. In the case of the NFC, they are in a much better position to do so, due to the paucity of documentation on the actual functioning of the peripheral.

Settings->ECC SRAM address. This defaults to 0x1FF, which is out of range of the NFC's SRAM buffer. It might actually alias to another buffer, or to an empty area, it's impossible to tell from the chip documentation. In any case, the maximum legal value is 0x11F.

Settings->Cache swap address 1/2. These default to 0x7FF, which are out of range of the SRAM buffer. Its not clear what effect it has when this is out of range, as there is very little about these settings in the documentation. It could be that it aliases to another of the NFC's SRAM buffers. The maximum legal value again is 0x11F, at least that's the best I can discern, as it appears from example code that this address is also a byte address divided by 8.

Re: bogus default values in Init_NFC

Petr_H — Wed, 21 May 2014 06:58:33 GMT

Hi,

the Peripheral Initialization Components represent a direct settings of peripheral registers and are implemented the way that their initial setup exactly corresponds to the after-reset values that are in the registers. This means that the initial values might not be valid in case that the peripheral registers have this after-reset values and the user has to change them, which is probably this case.

Best regards

Petr Hradsky

Processor Expert Support Team

Re: bogus default values in Init_NFC

bowerymarc — Tue, 10 Jun 2014 00:00:32 GMT

Consider the implications of that statement, Petr. If the PE components did not check and qualify it's input fields, it would be nothing more than a clunky forms engine with no 'expert' value whatever. Fortunately, that's not the case. Almost all of the fields are checked and either limit inputs to valid values, or warn the user when the values are out of range. This field, ECC Address, should also issue a warning when the values are out of range. And other values in this component.