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


c123 pcb annotated


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 part of osmocom-bb

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

pinout of MCSI port (NM_DAI)

Test points accessible from battery compartment

testpads of the compal calypso phones

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.

C123 Charger Connector

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

Files (6)
motorola_c123_hello_world.jpg View motorola_c123_hello_world.jpg 235 KB hello world on the C123 laforge, 01/21/2010 12:18 AM
compal_testpads.png View compal_testpads.png 51.7 KB testpads of the compal calypso phones laforge, 02/17/2010 08:10 AM
c123_pcb.jpg View c123_pcb.jpg 669 KB c123 pcb annotated laforge, 02/19/2010 09:10 AM
c123_charger_connector.jpg View c123_charger_connector.jpg 219 KB C123 Charger Connector vogelchr, 03/31/2010 05:24 PM
mcsi_pinout.jpg View mcsi_pinout.jpg 45.5 KB pinout of MCSI port (NM_DAI) steve-m, 08/26/2011 01:14 PM
c123_2.jpg View c123_2.jpg 13.1 KB laforge, 01/19/2022 08:50 AM

Updated by fixeria 3 months ago · 24 revisions

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