MC94MX21 Datasheet, PDF (7/98 Pages) Freescale Semiconductor, Inc – 333 and 350 MHz

Signal Descriptions
Table 2. i.MX21 Signal Descriptions (Continued)
Signal Name
Function/Notes
TEST_WB[4:3]
WKGD
These are special factory test signals. To ensure proper operation, leave these signals as no connects.
Battery indicator input used to qualify the walk-up process. Also multiplexed with TIN.
JTAG
For termination recommendations, see the Table “JTAG pinouts” in the Multi-ICE^® User Guide from ARM^® Limited.
TRST
TDO
TDI
TCK
TMS
JTAG_CTRL
RTCK
Test Reset Pin—External active low signal used to asynchronously initialize the JTAG controller.
Serial Output for test instructions and data. Changes on the falling edge of TCK.
Serial Input for test instructions and data. Sampled on the rising edge of TCK.
Test Clock to synchronize test logic and control register access through the JTAG port.
Test Mode Select to sequence the JTAG test controller’s state machine. Sampled on the rising edge of
TCK.
JTAG Controller select signal—JTAG_CTRL is sampled during the rising edge of TRST. Must be pulled
to logic high for proper JTAG interface to debugger. Pulling JTAG_CRTL low is for internal test purposes
only.
JTAG Return Clock used to enhance stability of JTAG debug interface devices. This signal is multiplexed
with 1-Wire, therefore using 1-Wire renders RTCK unusable and vice versa.
CMOS Sensor Interface
CSI_D [7:0]
CSI_MCLK
CSI_VSYNC
CSI_HSYNC
CSI_PIXCLK
Sensor port data
Sensor port master clock
Sensor port vertical sync
Sensor port horizontal sync
Sensor port data latch clock
LCD Controller
LD [17:0]
LCD Data Bus—All LCD signals are driven low after reset and when LCD is off. LD[15:0] signals are
multiplexed with SLCDC1_DAT[15:0] from SLCDC1 and BMI_D[15:0]. LD[17] signal is multiplexed with
BMI_WRITE of BMI. LD[16] is multiplexed with BMI_READ_REQ of BMI and EXT_DMAGRANT.
FLM_VSYNC
(or simply referred
to as VSYNC)
Frame Sync or Vsync—This signal also serves as the clock signal output for gate
driver (dedicated signal SPS for Sharp panel HR-TFT). This signal is multiplexed with BMI_RXF_FULL
and BMI_WAIT of the BMI.
LP_HSYNC (or simply Line Pulse or HSync
referred to as HSYNC)
LSCLK
Shift Clock. This signal is multiplexed with the BMI_CLK_CS from BMI.
OE_ACD
Alternate Crystal Direction/Output Enable.
CONTRAST
This signal is used to control the LCD bias voltage as contrast control. This signal is multiplexed with the
BMI_READ from BMI.
SPL_SPR
Sampling start signal for left and right scanning. This signal is multiplexed with the SLCDC1_CLK.
PS
Control signal output for source driver (Sharp panel dedicated signal). This signal is multiplexed with the
SLCDC1_CS.
CLS
Start signal output for gate driver. This signal is invert version of PS (Sharp panel dedicated signal). This
signal is multiplexed with the SLCDC1_RS.
REV
Signal for common electrode driving signal preparation (Sharp panel dedicated signal). This signal is
multiplexed with SLCDC1_D0.
MC94MX21 Technical Data, Rev. 1.4
Freescale Semiconductor
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