Motorola C123

The C123 seems to be one of many ODM phones that Motorola bought from Compal communications in Taiwan. It seems (nearly?) identical with the C118.

The internal name of the hardware is E88


  • GSM 900 / GSM 1800 dual-band
  • 101x45x21 mm, 86 grams
  • no GPRS
  • 920mAh Li-Ion battery
  • Ti Calypso/Iota/Rita chipset




The schematics (part of the Level 3 Service Manual) can be found at various mobile phone related
websites, including

GSM Chipset

  • DBB: Ti Calypso Baseband, D751749ZHH model (Calypso Lite G2), includes 256kBytes of internal SRAM
  • ABB: Ti TWL3025BZGR
  • RF: TRF6151C
  • RF PA: SKY77324-12

NOR Flash

  • Intel 28F160C3TD (16Mbits, i.e. 2 MByte) Advanced+ Boot Block Flash Memory (C3)
  • Data sheet will be in git



The display is a 96x64 pixels monochrome LCD, attached via I2C bus to the Calypso DBB chip.

The LCD controller inside the display is a Sitronix ST7558,
for which the data sheet is available. There is a community-based
driver implemented in PIC16 assembly (in our git repository)

Test Points

Test points surrounding Iota

  • TP4 -- BS_TDO, the JTAG TDO signal of the Iota (connected to TDI of Calypso)
  • TP5 -- Iota:TESTV pin
  • TP7 -- Uita:CK13M, connected from Calypso:CLK13M_OUT
  • TP29 -- Iota:ADIN1 (VADCID)
  • TP111 -- Iota:UDR (USP Rx), connects to Calypso:MCUDO
  • TP110 -- Iota:UEN (USP Enable), connects to Calypso:MCUEN0
  • TP112 -- Iota:ONNOFF
  • TP114 -- Intoa:ITWAKEUP, connects to Calypso:RTC_ALARM
  • TP113 -- Iota:RESPWONZ, connects to Calypso:RTSPWRONZ
  • TP116 -- Iota:TEST3
  • TP117 -- Iota:TEST4

Test points surrounding Calypso

  • TP11 -- Calypso:DSR_MODEM
  • TP12 -- Calypso:RTS_MODEM
  • TP23 -- Calypso:nCS4
  • TP46 -- Calypso:CLK32K_OUT, connects to Iota:CK32K
  • TP118 -- Calypso:EXT_IRQ, connects to Iota:INT2
  • TP115 -- Calypso:EXT_FIQ, connects to Iota:INT1
  • TP45 -- Calypso:SCLK (I2C)
  • TP30 -- Calypso:nSCS1 (I2C)
  • TP44 -- Calypso:SDO (I2C)
  • TP34 -- Calyspo:nCS2
  • TP48 -- Calypso:nCS3/INT4N
  • TP49 -- Calypso:VRDBB_1.5V


Test points accessible from battery compartment


On the C123 the following pads are usable
  • TP27 -- DLPWR (download power on), connects to Iota:RPWON
  • TP14 -- RxD Modem
  • TP13 -- TxD Modem
  • TP9 -- CTS Modem
  • TP39 -- GND
On most phones other pads are grounded and not usable (like in the scan above).
Known exceptions
  • C115 and C117 have all test pads
  • C155 has JTAG but not IRDA UART test pads

Charger Connector

The charger connector is a barrel-type with 3mm diameter and a segmented shaft. The top ring is not connected, the lower ring is GND. The top pin supplies +5V to the phone.


Antenna Connector

The antenna connector is a MS-147.

PCB photographs

Available from Pictures of each individual PCB layer can be found here: [] or at MotorolaC123PCB

motorola_c123_hello_world.jpg - hello world on the C123 (235 KB) laforge, 01/21/2010 12:18 AM

compal_testpads.png - testpads of the compal calypso phones (51.7 KB) laforge, 02/17/2010 08:10 AM

c123_pcb.jpg - c123 pcb annotated (669 KB) laforge, 02/19/2010 09:10 AM

c123_charger_connector.jpg - C123 Charger Connector (219 KB) vogelchr, 03/31/2010 05:24 PM

mcsi_pinout.jpg - pinout of MCSI port (NM_DAI) (45.5 KB) steve-m, 08/26/2011 01:14 PM