Maxim Integrated Secure Microcontroller - Manual (Page 144)

Secure Microcontroller User’s Guide
144 of 187
The D and F commands allow optional addresses to be entered. The syntax [Begin-Address [End-
Address]] is used to convey the following meanings:
a) No arguments: Begin-Address is set to 0 and End-Address is set to the range.
b) One argument: Begin-Address is set to the argument and End-Address is set to the range.
c) Two arguments: Begin-Address is set to the first argument and End-Address is set to the second
argument. This second address must not exceed the address value specified by the range.
In cases b and c, the End Address may not be less than the Begin Address, either implicitly or explicitly.
RAM will be addressed from 0 to 1FFF for 8kB RAM and from 0 to 7FFF for 32kB RAM. The range
determines the maximum value.
Error messages are printed as soon as errors are detected. All messages are preceded by the two
characters ‘E,’ and followed by a mnemonic description.
Commands are not processed until an entire command line is entered and terminated with a <CR>. No
command line can be greater than 16 bytes, which is the maximum number of characters in the K
command. Since a command line is not processed until a <CR> is entered, it can be edited with the delete
key, which does a destructive delete to the screen. Lines longer than 16 characters cause an error message
to be displayed and no action to be taken on the command line.
Only legal characters are echoed back to the screen. The legal characters are: 0123456789 <:>, <space>,
ABCDEFGHIJKLMNOPQRSTUVWXYZ, and <delete>. Backspace characters (<BS>) are converted to
delete characters. The horizontal tab character is converted to space. Lower case alphabetic characters are
converted to upper case alphabetic.
The <delete> character is executed as a <BS> <space> <BS> when possible in command mode. This
causes the character to be overprinted on a hardcopy device. The <CR> character generates a <CR>
<LF> pair.
The serial bootstrap loader responds to XOFF characters by stopping transmission as soon as the
character is received. A control-C or an XON resumes serial transmission. The serial bootstrap loader
does not transmit an XOFF character. The program is able to keep up with input as long as the receiver
can keep up with its output. The receiver should be programmed to quit transmission after it sends an
XOFF and transmit anything before sending an XON.
Intel hex data is not echoed unless the trace mode is toggled on.
Important Application Note
Because different bootstrap loader commands have different execution times, the communication
interface must be response-driven rather than employ fixed-time delays. This is important if the system
designer writes his or her own software to communicate with the bootstrap loader. After sending a
command to the microcontroller, the communication software must wait for a prompt ‘>’ before sending
the next command. The obvious exceptions to this are the load and verify commands, which do not
require the prompt before sending the Intel Hex file. Also note that the bootstrap loader can generate a
number of error messages in response to different events. User-authored communication software must
continually monitor the microcontroller for error messages and react accordingly.