Small Size	Low Power, Simple to use
Buffalo Monitor and Basic11 Interpreter	CPU_3A FAQ
Create powerfull HC11 applications without expensive development tools
CPU_3A* Info - Connections - Prices - Downloads -/- Development Board - Prices - Downloads Update & Correction notes
The battery shown is an optional extra. The battery is not supplied as standard. The module can be supplied with or without the header pins installed. Supplied with header pins installed unless otherwise requested. Think of it as a single chip processor. Simply build your application around it. It's well suited to classroom and hobby use because of the large amount of RAM for a low cost unit. This allows code to be developed and tested on a very short cycle. Code then load and test, and back to the code is very quick. Once the code is working in RAM it can be converted to run from Flash memory. A FEW DETAILS INTRODUCTION The CPU_3A is a small general purpose processor module based on the popular Motorola 68HC11 microcontroller. It's designed to be mounted on another circuit board. This board provides power and interfacing to the real world. The HC11 has a good assortment of built in I/O, including SCI and SPI communications ports, 8 bit analog to digital conversion, a versatile timer system and digital I/O lines. The majority of these are accessible on the CPU_3A. The HC11 is operated in expanded mode. This mode uses some of the digital I/O lines to interface to the on-board RAM and Flash memory. The CPU data bus, part of the address bus and a CPU generated chip select line are available on the header connector. This allows additional I/O and interface devices to be connected to the CPU. 512K bytes of Flash memory and 128K bytes or RAM provide program and variable storage. The Flash and RAM can be used for data logging. Flash and RAM memory are accessed as banks of 64K/32K bytes. The on-board RAM and real-time-clock can be battery backed protecting time, date and data from power failure. Jumpers allow the HC11 boot loader to be used to initialise the CPU and memory and to load program code into Flash RAM and the CPU EEPROM memory. The module can then be restarted and operated normally. There are various utilities that allow Motorola S19 files to be loaded into RAM from a PC and executed. PROGRAM DEVELOPMENT The CPU_3A can be used without the need for expensive development tools. An assembler such as AS11 available free from Motorola, or a compiler will produce an S19 output file that can be transferred to the CPU_3A using the provided loader utility. The loader can automatically run the downloaded program. Using AS11 or MiniIDE you can develop and test your own applications in HC11 assembly language. This is not as difficult as you may have heard. The CPU_3A allows you to quickly load and test your program in RAM. This is quicker than loading the Flash memory repeatedly. Once the program is ready it can be re-assembled and loaded into Flash memory where it will stay. There are a number of suppliers of commercial assemblers, compilers, simulators and emulators. Many of these are suitable for large project development, but not cost effective for small projects or for hobby or classroom experimentation. BUFFALO & BASIC 11 The Buffalo monitor is a very usefull development tool which allows program code being developed, to be loaded into RAM and tested. The results can be checked, the code modified and another test done. Buffalo makes this process quite simple and relatively quick. Basic11 is a simple but powerfull Basic language interpreter that resides in Flash memory on the CPU_3A board. Using a communications program (like HyperTerminal) connected to the CPU_3A board, the Basic program is written and tested. When complete, the program can be saved to Flash memory. The board is then able to automatically run the basic program whenever power is applied. FEATURES Small size = 81mm wide x 45mm deep x 13mm high (with jumpers) Connections = two 26 way, 0.1 inch pitch, double row headers Mounting = normally supported by the two connection headers Construction = double sided circuit board with surface mount components CPU & clock = Motorola MC68HC11F1CFN4 with an 16MHz crystal Mode = expanded mode, the HC11F1 is non-multiplexed Flash memory = 512K bytes in eight 64K banks (ST 29F040) RAM memory = 128K bytes in four 32K banks Real-time-clock = Holtek HT1381 Battery backup = optional on-board for RTC and RAM Power input = single 10 to 15 Volt DC @ 20mA (average) Voltage regulator = 78L05, 5 Volt on-board Reset = under-voltage reset and reset button Boot loader using Windows HC11Boot (supplied) or other utility OPTIONAL BATTERY BACKUP The CPU_3A supports RTC and RAM battery backup. The battery connections are above and below the Flash memory chip. This allows a suitable battery to be soldered directly into position. The battery can be any suitable standard lithium, rechargable lithium or nicad, 3V battery. Alternatively, an external 3V battery can be wired via the expansion header and a simple charge control circuit. Because the battery is a significant cost and not required in many applications, it is not supplied as standard with the CPU_3A. KBD,I/O EXPANSION HEADER This 5-pin header is intended to be used to provide a serial I/O expansion interface. It is compatible with a number of other PMB expansion modules. It can also be used to connect a standard PC keyboard with a suitable connector. This is a software driven interface. TO MAKE IT GO To make the CPU_3A operational you need a 10 to 15 volt regulated power supply and an RS-232 interface. PMB can supply details if required. A PC with a serial port is connected to the CPU_3A. A download utility is then able to initalise the CPU_3A and send your program code through to RAM or Flash memory. Each CPU_3A module is supplied with the Buffalo monitor preloaded into flash memory and tested. UPDATES & CORRECTIONS Table of connections updated to correct reverse order lising of A0-A7 of expansion header. RAM address line A14 is shown on the circuit diagram connected to the bank select latch. It is actually connected to the CPU address line A14. The port-E terminal connections on the first version development board are incorrectly labeled. The order is E7, E3, E6, E2, E5, E1, E4, E0, with E7 at the corner of the board. CAUTION CPU_3A* I/O connections are rated at 5 volts. Only the input power supply is able to withstand a higher voltage, and then not more than 15VDC. I/O connections will be damaged if more than 5 Volts is applied. The Development board (below) provides protection for the CPU_3A. This is ideal for experimenting and classroom use. The development board (EVB_3A see below) does provide signal conditioning and protection to the CPU_3A. The development board is recommended for development and experimentation.

CONNECTIONS The following table shows the function assigned to each of the 57 connector pins. If you are not familiar with the HC11, the manual or data sheet will be required to sort out some of the meaning.

Left End Header (next to CPU) Power in and CPU I/O
1	PE7	direct connect	analog input	.
2	PE3	direct connect	analog input	.
3	PE6	direct connect	analog input	.
4	PE2	direct connect	analog input	.
5	PE5	direct connect	analog input	.
6	PE1	direct connect	analog input	.
7	PE4	direct connect	analog input	.
8	PE8	direct connect	analog input	.
9	XIRQ	direct connect	input	non-maskable interrupt
10	IRQ	direct connect	input	interrupt, shared with kbd,i/o port
11	PA0	direct connect	digital I/O	.
12	PA1	direct connect	digital I/O	.
13	PA2	direct connect	digital I/O	.
14	PA3	direct connect	digital I/O	.
15	PA4	direct connect	digital I/O	.
16	PA5	direct connect	digital I/O	.
17	PA6	direct connect	digital I/O	.
18	PA7	direct connect	digital I/O	.
19	PD4	direct connect	digital I/O	.
20	PD5	direct connect	digital I/O	.
21	PD2	direct connect	digital I/O	.
22	PD3	direct connect	digital I/O	.
23	PD0	direct connect	RXD	SCI, serial port
24	PD1	direct connect	TXD	SCI, serial port
25	+V	power supply	.	+10 to +15 volts DC (main supply)
26	COM	power supply	.	common
Right End Header (next to reset button) System Expansion and control signals
1	+5V	supply out	.	maximum load = 75mA
2	COM	power supply	.	common
3	RST	reset	reset	.
4	A10	direct connect	address bus	.
5	A9	direct connect	address bus	.
6	A8	direct connect	address bus	.
7	A7	direct connect	address bus	.
8	A6	direct connect	address bus	.
9	A5	direct connect	address bus	.
10	A4	direct connect	address bus	.
11	A3	direct connect	address bus	.
12	A2	direct connect	address bus	.
13	A1	direct connect	address bus	.
14	A0	direct connect	address bus	.
15	CE	chip enable	.	.
16	VBAT	.	.	memory backup battery
17	E	E clock	control signal	.
18	R/W	read/write	control signal	.
19	D0	direct connect	data bus	.
20	D2	direct connect	data bus	.
21	D3	direct connect	data bus	.
22	D4	direct connect	data bus	.
23	D5	direct connect	data bus	.
24	D1	direct connect	data bus	.
25	D7	via 1K resistor	data bus	.
26	D6	direct connect	data bus	.
KBD,I/O Header (next to CPU) Serial I/O expansion
1	+5V	supply out	.	max load = 50mA
2	COM	power supply	.	common
3	DAT	via 470R resistor	exp data	to CPU IRQ
4	CLK	via 470R resistor	exp clock	to CPU PG2 (shared with RTC)
5	IRQ	via 470R resistor	exp interrupt	to CPU PG3
.	.	.	.	.

example of vertical mounting

rear view

assembled modules	package	part number	1 to 11	12 to 48	49 up
CPU_3A module only, HC11F1, 128K RAM, 512K Flash	-	YTMGPC3AM	$79.00 email	email	email
CPU_3A + Development Bd Std EVB_5A1 development board	EVB_5A1	YTMGPC3AP	$165.00 email	email	email

Files available for Download
Circuit Diagram (pdf)	HC11Boot Loader (zip)	Memory map (.asm)
Code Examples (zip)	Clock data sheet (pdf)	Reset/Boot Operation (pdf)
F.A.Q	Buffalo Monitor (zip)	CPU_3A2 Connections (pdf)
Basic11 Interpreter	RTC code example (asm) new	To other download page

DEVELOPMENT BOARD Note - We've updated the Development Board Updated info comming soon - EVB_5A1 The EVB_3A board supports the CPU_3A module for development, experimentation and programming.
FEATURES Onboard 5 Volt power supply from a 9V to 18V DC input One RS-232 port (9 pin D), with LED data indicators On-board piezo buzzer Screw terminals for ports E, A and part of D. I/O via screw terminals includes on-board signal conditioning. Expansion connection via box headers for ribbon cable connection. Three high current outputs (mosfet, open drain, 1A max.) The CPU_3A module plugs into two 26 way sockets on the board Size = 140 mm by 95 mm (approx) The development board is supplied on it's own or with a CPU_3A cpu module When supplied with, the cpu module can be socketed or soldered to the development board. The development board is supplied less power source, serial cable and CPU_3A module. To make use of the board, a 12V DC plug-pack or bench supply, 9 pin male to PC serial cable and a CPU_3A module will be required.

assembled modules	package	part number	1 to 11	12 to 48	49 up
STD Development board only, for CPU_3A module	EVB_5A1	YMEVB5A1DB	$98.00 email	email	email
CPU_3A* + Development Bd Std EVB_5A1 development board	EVB_5A1	YTMGPC3AP	$165.00 email	email	email

Files available for Download
Circuit Diagram (pdf) updated	Operating Instructions (pdf)	.
EVB_3A3 board overlay (pdf)	EVB_3A4 board overlay (pdf)	.

NOTES: Our numbering system CPU_3A2. "CPU_3" describes the product "A" describes the board or module "2" describes the revision.

last updated: 06 May 2009