In bringing up a new SOC there are many challenges. You need a good part of the system up and
running prior to having any kind of console/debug monitor. This is normally because you need
a good part of the SOC functional before you can run code. uMON helps you to debug your SOC
earlier in the process. uMON just requires a boot device, working uart and the SOC. It uses the
registers in the SOC as a stack for input from the console(UART). It can then execute a number of
commands (fill, dump, compare, etc..) that will allow you to debug the rest of the SOC.

UMON is a simple monitor that runs w/o the need of any ram. It uses three registers for a stack space for commands.

In order to push items onto the ‘stack’ you simply enter a number at the | prompt.

0ee00000

This will push the value 0x0ee00000 onto the top of the stack and push any other values currently on the stack down the stack.

If this was the stack prior to the above:

AA55AA55 <- Top

00001000

00000000 <- Bottom

After entering the number above the stack would be:

0EE00000 <- Top

AA55AA55

00001000 <- Bottom

NOTE: Entering any number that begins with a Hex digit (A-F) must be preceded by a 0.

Example: AA55AA55 would have to be entered as 0AA55AA55

At any time you can enter a . and it will dump out the current stack top->middle->bottom

Most commands can be stopped by pressing s on the console.
This will bring up a prompt: Type '^q' or 'q' to continue, '.' to terminate.

Compare data command. This command compares data to memory locations pointed to by address range contained on the top of stack.

Usage:

xxxxx - Compare start address

yyyyy - Compare last address

zzzzz - Compare pattern

c

If a non-match is found it will print to the console the address and the mismatched data.

If all data matches it will return to the prompt.

Examine data command. This command fetches and prints the data from the memory location pointed to by address contained on the
top of stack. It will then let you modify the data at the
address or step to the next data in memory. The address on the stack
is incremented by the size of the item fetched.

It has three usages one for a byte, half word, word and doublw word

Usage:

xxxx – Address to examine

eb - fetches a byte

xxxx – Address to examine

eh - fetches a half word

xxxx – Address to examine

ew - fetches a word

xxxx – Address to examine

ed - fetches a double word

Increment fill data command. This command stores data to memory locations pointed to by address range contained on the top of stack.
It will increment the pattern by 1 for each location stored too

Usage:

xxxxx - fill start address

yyyy - fill last address

zzzzz - Fill pattern

ib - fill with bytes

ih - fill with shorts

iw - fill with words

increment compare data command. This command compares data to memory locations pointed to by address range contained on the top of stack. It will
increment the pattern by 1 for each location compared

Usage: xxxxx - Fill start address

yyyyy - fill last address

zzzzz - Fill pattern

nb - fill with bytes

nh - fill with shorts

nw - fill with words

Fill data command. This command stores data to memory locations pointed to by address range contained on the top
of stack. It fills on a word boundary

Usage:

xxxxx - Fill start address

yyyyy - fill last address

zzzzz - Fill pattern

f

This code segment jump to the location pointed to the top of the stack

Usage:

xxxx – Jump Address j

Load data command. This command fetches and prints the data from the memory location pointed to by address contained in the
top of stack. The address on the stack is incremented by the size
of the item fetched.

Usage:

Xxxx – Address to start loading from

lb - fetches a byte

lh - fetches a half word

lw - fetches a word

Memory test loop. The range of the loop is specified by TOS
and NOS. This test first writes a pattern through the range of
address and then reads and compares to see if the pattern is
correct. This will test address lines and if refreash is happening
often enough. A good test is to pick a large range (1 meg+) and test it for bytes, half words and words. Let run over night each time.
Pattern starts at 0x00 and increments by 1 for each address written.

Usage:

xxxxx - start address

yyyyy - end address

mb - writes a byte

mh - writes a half word

mw - writes a word

This code segment enters into an endless loop to read the
location pointed to by the TOS.
NOTE: There is no way to break out of this cmd other than a power cycle.

Usage:

xxxx – Address to read forever and ever..

rb - fetches a byte

rh - fetches a half word

rw - fetches a word

rd – fetches a double word

Store data command. This command stores the data on the top of the stack
into memory by the location point to by address contained in the next to the
top of stack. The stack is popped so that only the address remains on the stack. The address on the stack is incremented by the size of the item stored. NOTE: This can be used in a script to program a series of registers with values

Usage:

xxxx – Address to store to

yyyy – Data to store

sb - stores a byte

sh - stores a half word

sw - stores a word

Transfer data command. This command transfers data between locations pointed to by address range contained on the top of stack.

Usage:

xxxxx - block source start address

yyyyy - block source last address

zzzzz - block destination address

t

Endless loop to write the value in TOS to the location pointed to by the NOS. NOTE: There is no way to break out of this command other than a power cycle

Usage:

xxxx - Write Address yyyy – Data to Write

wb - writes a byte

wh - writes a half word

ww - writes a word

This code segment enters into an memory test loop. The range of the loop
is specified by TOS (S2) and NOS (S1). This test writes a word and immediately
reads it to test for refreash arbitration problems. To catch an arbitration
problem set the logic analyzer to trigger on the branch to memerror.
The write or read that caused the problem will be close by.

Usage:

xxxx – Start Address

yyyy – End Address

x

This code segment prints whats in the stack and leaves the stack alone.

Usage:

.

Dump data command. This command fetches and prints the data from the memory locations pointed to by address range contained
on the top of stack.

Usage:

xxxxx - Dump start address

yyyyy - Dump last address

d