EM6607 EM Microelectronic, EM6607 Datasheet - Page 28

• Manufacturer Part Number: EM6607
• Description: Ultra-low power microcontroller
• Manufacturer: EM Microelectronic

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EM6607
12.1 SWB Automatic send mode
Automatic mode enables a buffer on a predefined length to be sent at high transmission speeds ( up to 16khz). In this mode
user prepares all the data to be sent (minimum 8 bits, maximum 256 bits) in RAM. The user then selects the clock speed,
sets the number of data nibbles to be sent, selects automatic transmission mode (AutoSWB bit set to 1) and enters
STANDBY mode by executing a HALT instruction. Once the HALT instruction is activated the SWB peripheral module sends
the data in register SWBuff followed by the data in the RAM starting at address 00 up to the address specified by the bits
size[5:0] located in the LowSWB, HighSWB registers.
During automatic transmission the general INTEN bit is disabled automatically to prevent other Interrupts to reset the
standby mode. At the end of automatic transmission EM6607 leaves standby mode and sets TestVar[3] high. TestVar[3] =
1 is signaling SWB transmission is terminated. Once the transmission is finished, do not forget to enable the general INTEN
bit if necessary.
The data to be sent must be prepared in the following order:
First nibble to be sent must be written in the SWBuff register . The other nibbles must be loaded in the RAM from address 0
(second nibble at adr.0, third at adr.1,...) up to the address with last nibble of data to be send = "size" address. Max. address
space for SWB is 3E ("size" 3E hex) what gives with SWBuff up to 64 nibbles (256 bits) of possible data to be sent. The
minimum possible data length we can send in Automatic SWB mode is 8 bits when the last RAM address to be sent is 00
("size" = 00)
Once data are ready in the RAM and in the SWBuff, user has to load the "size" (adr. of the last nibble to be send - bits
size[5:0]) into the LowSWB and HighSWB register together with AutoSWB bit = 1.
Now everything is ready for serial transmission. To start the transmission one has to put the EM6607 in standby mode with
the HALT instruction. With this serial transmission starts. When transmission is finished the TESTvar[3] (can be used for
conditional jumps) becomes active High, the AutoSWB bit is cleared, the processor is leaving the Standby mode and
INTEN is switched on.
Figure 15.
Automatic Serial Write Buffer transmission
The processor now starts to execute the first instruction placed after the HALT instruction (for instance write of SWBuff
register to clear TESTvar[3]), except if there was a IRQ during the serial transmission. In this case the CPU will go directly in
the interrupt routine to serve other interrupt sources.
TestVar[3] stays high until SWBuff is rewritten. Before starting a second SWB action this bit must be cleared by performing
a dummy write on SWBuff address.
Because the data in the RAM are still present one can start transmitting the same data once again only by recharging the
SWBuff , LowSWB and HighSWB register together with AutoSWB bit and putting the EM6607 in HALT mode will start
new transmission.
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