11.0 In-circuit Programming Specification15,16
The ACEx microcontroller supports in-circuit programming of the
internal data EEPROM, code EEPROM, and the initialization registers.
An externally controlled four wire interface consisting of a LOAD
control pin (G3), a serial data SHIFT-IN input pin (G4), a serial data
SHIFT-OUT output pin (G2), and a CLOCK pin (G1) is used to access
the on-chip memory locations. Communication between the ACEx
microcontroller and the external programmer is made through a 32-
bit command and response word described in Table 15.
The serial data timing for the four-wire interface is shown in Figure
31 and the programming protocol is shown in Figure 30.
11.1 Write Sequence
The external programmer brings the ACEx microcontroller into
programming mode by applying a super voltage level to the LOAD
pin. The external programmer then needs to set the LOAD pin to 5V
before shifting in the 32-bit serial command word using the SHIFT_IN
and CLOCK signals. By definition, bit 31 of the command word is
shifted in first. At the same time, the ACEx microcontroller shifts out
the 32-bit serial response to the last command on the SHIFT_OUT
pin. It is recommended that the external programmer samples this
signal tACCESS (500ns) after the rising edge of the CLOCK signal.
The serial response word, sent immediately after entering program-
ming mode, contains indeterminate data.
After 32 bits have been shifted into the device, the external
programmer must set the LOAD signal to 0V, and then apply two
clock pulses as shown in Figure 30 to complete program cycle.
The SHIFT_OUT pin acts as the handshaking signal between the
device and programming hardware once the LOAD signal is
brought low. The device sets SHIFT_OUT low by the time the
programmer has sent the second rising edge during the LOAD =
Table 15: 32-Bit Command and Response Word
0V phase (if the timing specifications in Figure 30 are obeyed).
The device will set the R bit of the Status register when the write
operation has completed. The external programmer must wait for
the SHIFT_OUT pin to go high before bringing the LOAD signal to
5V to initiate a normal command cycle.
11.2 Read Sequence
When reading the device after a write, the external programmer
must set the LOAD signal to 5V before it sends the new command
word. Next, the 32-bit serial command word (for during a READ)
should be shifted into the device using the SHIFT_IN and the
CLOCK signals while the data from the previous command is
serially shifted out on the SHIFT_OUT pin. After the Read com-
mand has been shifted into the device, the external programmer
must, once again, set the LOAD signal to 0V and apply two clock
pulses as shown in Figure 30 to complete READ cycle. Data from
the selected memory location, will be latched into the lower 8 bits
of the command word shortly after the second rising edge of the
Writing a series of bytes to the device is achieved by sending a
series of Write command words while observing the devices
Reading a series of bytes from the device is achieved by sending
a series of Read command words with the desired addresses in
sequence and reading the following response words to verify the
correct address and data contents.
The addresses of the data EEPROM and code EEPROM loca-
tions are the same as those used in normal operation.
Powering down the device will cause the part to exit programming
bits 31 – 30
bits 27 – 25
bits 23 – 19
bits 18 – 8
bits 7 – 0
Input command word
Must be set to 0
Set to 1 to read/write data EEPROM, or the
initialization registers, otherwise 0
Set to 1 to read/write code EEPROM,
Must be set to 0
Set to 1 to read, 0 to write
Must be set to 0
Address of the byte to be read or written
Data to be programm ed or zero if data is to be read
Output response word
Same as Input command word
Programmed data or data read at specified address
15 For further information see Application Note AN-8005.
16 During in-circuit programming, G5 must be either not connected or driven high.
ACE1202 Product Family Rev. B.1