Motorola C155

The C155 seems to be one of many ODM phones that Motorola bought from Compal communications in Taiwan. It is of the same family as the C118, C123, etc.

The internal name of the hardware is E99.

Compared to the MotorolaC123, this phone offers
  • a color LCD (same resolution)
  • four times bigger RAM (2MByte)
  • four times bigger NOR Flash (8MByte)
  • JTAG seems accessible, though this is unconfirmed


  • GSM 900 / GSM 1800 dual-band
  • 101x45x21 mm, 86 grams
  • GPRS
  • 920mAh Li-Ion battery
  • Ti Calypso/Iota/Rita chipset


c155 pcb
Hello world program on the C155 LCD


Schematics ( Sch_C155_A3_C_L3_1.0.pdf ) can be found on this site: (among others). The captcha is a b**** but it'll work in the end.

GSM Chipset

  • DBB: Ti Calypso Baseband, D751749GHH model (Calypso Lite G2), includes 256kBytes of internal SRAM
  • ABB: Ti TWL3014C
  • RF: TRF6151C
  • RF PA: SKY77324-12

NOR Flash + SRAM

  • Intel RD38F2030W0ZBQ1
    • 64MBit NOR (8 MByte), bottom boot
    • 16Mbit SRAM (2 MByte)
  • Data sheet is in our git repository


The display is a 98x67 pixels CSTN color LCD (12Bit, 4096 Colors), which is attached via UWire to the Calypso DBB chip.

The LCD controller inside the display is a Solomon SSD1783 (using an extended Epson commandset), for which the datasheet is available at "We now have a basic text-only driver.

Audio Ringtone Chip

It uses a Sunplus SPMA100B"httpwwwdensitroncomuploadedFilesDisplaysSupportSSD1783pdf. chip. There is no datasheet available from Sunplus, but however, the Chip is pin-compatible with the Yamaha YMU759 MA-2 (Mobile Audio 2). But even for this chip there is no register level datasheet available.

Test Points

Test points accessible from battery compartment

Left Row of pins (from left to right
  • TP108 -- GND
  • TP29 -- GND (used to be VADCID)
  • TP37 -- GND (used to be Rx IRDA)
  • TP27 -- DLPWR (download power on), connects to Iota:RPWON
  • TP36 -- GND (used to be Tx IRDA)
  • TP10 -- DTR Modem
Right row of pins (from left to right)
  • TP8 -- TDI JTAG
  • TP11 -- DSR Modem
  • TP9 -- CTS Modem
  • TP18 -- TMS JTAG
  • TP13 -- TxD Modem
  • TP16 -- TDO JTAG
  • TP21 -- RTS Modem
  • TP17 -- TCK JTAG
  • TP14 -- RxD Modem
  • TP3 -- DLPWR

PCB photographs

Available from "h2. Misc Notes


The RAM loader of the C155 assumes that the payload is a THUMB binary. osmocon"httplaforgegnumonksorgphotoalbumdevicesmotorola_compalc155 thus always prefixes the payload with 32bit of
object code to switch back to ARM mode before jumping to the start routine.

c155_pcb.jpg - c155 pcb (872 KB) laforge, 02/19/2010 06:31 PM

osmocom_c155.jpg - Hello world program on the C155 LCD (47.9 KB) laforge, 03/02/2010 09:21 AM

compal_testpads.png (51.7 KB) laforge, 02/21/2016 10:34 AM