To program the gm5221 the content of the external ROM is generated using Genesis softwaredevelopment tools G-Wizard and OSD-Workbench. G-Wizard is a GUI-based tool for capturing systeminformation such as panel timing, support modes, system configuration, etc. OSD-Workbench is a GUIbased tool for defining OSD menus and functionality.
Genesis recommends using Paradigm compiler (
http://www.devtools.com) to compile the firmwaresource code into a hex file. This hex file is then downloaded into the external ROM using In-System-Programming (Genesis debug software G-Probe communicates with the OCM which in turn programs aFLASH ROM in the system using the ROM_WEn signal) or using commercially available ROMprogrammers.
gm5221 is equipped with an embedded ROM bootstrap function from which to boot when external ROMis not present or it does not contain data. It is always recommended to boot from embedded ROM (seedescription of ROM_ADDR16 in Table 16).
The bootstrap function works in the following way. The embedded ROM firmware first looks for a‘signature’ in external ROM (either parallel ROM or serial ROM depending on the programming ofROM_ADDR15 – see Table 16). The ‘signature’ is the ASCII values for the character string “xROM”starting at address 0x800F0. If this signature is found then it performs a CRC check. If CRC is valid thenit jumps to external ROM address 0x80100.
If the signature is not present (or bootstrap value of ROM_ADDR7 is one) then the embedded firmwaredoes not jump to external ROM. In this case it runs in its own loop that supports debugging commands(using G-Probe debugging software available from Genesis) over either the UART port (see section4.13.6) or the DDC2Bi port (see section 4.13.5).
The gm5221 has hardware to program FLASH ROM devices. In particular, the ROM_WEn pin can beconnected to the write enable of the FLASH ROM. The embedded boot firmware (see section 4.13.2above) performs the writes.
The gm5221 OCM has an integrated Universal Asynchronous Remote Terminal (UART) port that can beused as a factory debug port. In particular, the UART can be used to 1) read / write chip registers, 2) read/ write to NVRAM, and 3) read / write to FLASH ROM (In-System-Programming).
Hardware support is provided for DDC2Bi communication over the DDC channel of either the analog orDVI input ports. The specification for the DDC2Bi standard can be obtained from VESA(
www.vesa.org). The DDC2Bi port can be used as a factory debug port or for field programming. Inparticular, the DDC2Bi port can be used to 1) read / write chip registers, 2) read / write to NVRAM, and3) read / write to FLASH ROM (In-System-Programming).
The factory programming or test station connects to the gm5221 through the Direct Data Channel (DDC)of the DSUB15 or DVI connectors. For example, the PC can make gm5221 display test patterns (seesection 4.5). A camera can be used to automate the calibration of the LCD panel.