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E8a Mini/Micro

The E8a-Mini connector is a small footprint version of the Renesas E8a connector. It is electrically identical to the E8a, but uses an 0.050 inch pitch female connector instead of an 0.100 inch pitch male connector. The target board connectors look like this (male target header is 0.100" pitch, female target header is 0.050" pitch):

E8a E8a-Mini
3 4
5 6
7 8
9 10
11 12
13 14
4 3
6 5
8 7
10 9
12 11
14 13

The target board connector is Sullins SFH31-NPPB-D07-SP-BK or equivalent. The E8a's connector is either Sullins SBH31-NBPB-D07-SM-BK (SMT) or SBH31-NBPB-D07-ST-BK (PTH/Edge). This is a 50 mil pitch keyed connector. The target board must reserve enough space for the male connector - at least 0.5 by 0.25 inches (the connector is 0.468 by 0.221 inches). The target connector allows for any 14 pin 50 mil pitch male connector, although proper insertion orientation (pin 1 to pin 1 etc) must somehow be enforced.

Serial Mode 2/3 Micro Connector

3 4
5 6
4 3
6 5

Target MCU Connections
PinA<->TMode 2Mode 3
2 <-- TXD MODE
3 --- GND GND
4 --> RXD  
5 <--> VCC VCC
6 --> MODE  

This connector is even smaller, although it can be implemented with 0.1 inch pitch (male on target) as well as 0.050 inch (female on target). The pinout is limited to chips which support serial mode 2 (uart) or 3 (single wire) programming or other serial-based protocols. Most R8C, M16C, M32C, R32C, and RX chips, as well as many SH and H8 can be programmed this way. Note that some chips may require additional circuitry to support a single "mode" signal in some cases; for example, using an M32C in expanded-bus mode requires an additional transistor or inverter on the board to generate all the required signals.

The connector is not keyed (although keyed connectors may be used) so as to save space. Note that the pinout was carefully designed to be safe if the connector is inserted backwards.

Note that there are two wiring options for this connector. Targets which require mode 3 programming should use the "Mode 3" pinout, where the MCU's MODE pin is connected to the adapter's TXD pin, instead of connecting the MCU's TXD pin there. Such targets will not have the UART functionality available, and thus can only be programmed, not interacted with.


Since the E8a-side connector is available in both surface mount and leaded, it allows for various types of adapters to the original E8a male target connector. Either connector can be used for adapters that hang off the edge of the board (adapter board parallel to the target board). The leaded connector allows for a vertically mounted adapter using a 32 mil thick PCB, for crowded boards.

Adapters to use E8a-Mini interface boards (below) with standard 0.1" pitch E8a connectors are also available.

Target Interface Boards

In addition to the stock E8a emulator pod, the E8a-Mini system defines a number of small target interface boards which provide programming and console access. These boards are based on small USB interface chips, use vertically-mounted PCBs, and plug directly into the target board without additional cables. These boards primarily use serial mode 2 (async Tx/Rx) programming, but some offer serial mode 3 (single wire). Power may come from the target board or the USB bus depending on the model.


These boards demonstrate the E8a-Mini and Serial Mode Micro connectors and adapters, except the one in the lower right, which is a combined board.

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  Copyright 2010   by DJ Delorie     Updated Oct 2010