Page 102 - The Art of Designing Embedded Systems

Firmware Musings 89

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Xdtl
xdh, set port UxfR34-0x80
xdh, set port OxfO43-Ox30
$xdb> set port Oxf043-0x42
,xdb> set port Oxf043-0x82
xdb) set part Oxf040-55
,xdb) set prt Oxf040-55
xdb> sat part Oxf834-0
'xdb> -

FIGURE 5-1 Hacking a peripheral driver.

Then write a shell of a driver in the selected language. Take the in-
formation gleaned from the databook and proven in your experiments to
work, and codify it in code once and for all. Test the driver. Get it right!
Now you've successfully created a module that handles that hard-
ware device.
Master one portion of a device at a time. On a UART, for example,
figure out how to transmit characters reliably and document what you

FIGURE 5-2 Hacking a peripheral driver.
FIGURE 5-2 Hacking a peripheral driver.